Part of keeping costs low is to avoid having to go back again later to take care of things that weren't covered the first time. Make your agreement as future-proof as you can. I think a good rule of thumb is to define a default action and specific dates/times for everything (or at least as much as you can).
For example, with the house/mortgage, hypothetically you agree that you'll keep the house and he will sign a quit-claim deed. Great! But what happens if he refuses to sign? Be specific that it must be signed by specific-date or this-action-happens. Maybe it's that he becomes responsible for your reasonable costs in going back to court to coerce him to do it (that might be the default anyway, but being explicitly written would remove your need to prove his responsibility to the Court). Another hypothetical scenario: he keeps the house and you're to sign a quit-claim deed. You would obviously want him to refinance to get your name off the mortgage (to free up your credit to get your own house/rental). Here it's probably more obvious why you need to be specific about default actions since you'll be damaged if he doesn't follow the order (i.e. refinance) because he could hurt your credit rating if he pays late (the court can not order the debt holder to remove your liability). In that case you might want to define a deadline for him to refinance and upon proof of the refinance you will sign the quit-claim deed (never, ever, ever sign the quit-claim deed until your name is off the mortgage, btw) and that if he hasn't done it by deadline-date that the default action is the house shall be listed for sale and specify the division of the proceeds after the sale.
For future-proofing the agreement (primarily in terms of the division of parenting time) consider not only what your kids need now (cover every minute of the day, perhaps saying the children are with you subject to dad's right to parenting time during these-times--use specific time references, like when the child is released from school, when specific times are unknown or subject to change), but also what they'll need 5, 10, 15 years from now. You know schedules change (beginning kindergarten, after-school sports, fine arts extracurriculars, church rituals if it applies to your family) and if you can cover the obvious needs now, you'll neither have to come up with the money to change it later nor throw a court-battle-wrench into the parenting relationship you have to build and maintain with STBX. Cover who takes the kids, who pays what and in what circumstances ... and what if you disagree on whether DS will take piano or karate, what happens, who decides, who pays and how much? Google for your state's default parenting agreements to get an idea of what is assumed--though it can still be helpful to have it explicitly in your agreement just so everyone knows "the rules" going forward. Make sure everything that made its way into the agreement has an automatic out--for example if there's daycare costs included, they should automatically expire when child to which they apply turns 12 years old--so you don't have to incur more legal fees to have the Order updated.
On the other hand, if you see that he's going to make a big fuss (that you're going to have a long legal fight) to sort out what will happen in 10 years, you could reserve those things for later. Keep in mind that it's relatively easy to get a court order updated to reflect the new status quo, once it's been happening for over a year. So if it looks like he's going to nearly bankrupt you fighting to get the kids half the time and you know he can't or won't actually take them that much, and if you can manage to make ends meet with the reduced child support for a year or two, you can probably more easily and cheaply get the order updated to show that he only takes the kids 4 days a month once it's been going on for a year, than to convince the Court to only grant him 4 days at the onset.
Don't be shy in telling your attorney you want to keep costs down. Ask if you can draft your documents (i.e. typing)--their assistant's billing rate is probably over $100/hr. Some won't let you use their legal template but if you can get it to the point of copy-paste (you don't do any formatting) you could save some there.
One mistake I've seen people make is to try to go too bargain basement on the attorney. You certainly can stand to save some money in the long run if they can get the job done quick and in your favor, rather than an attorney who might have a lower billing rate but takes twice (or more) as long to get it done or requires multiple hearings to get what you "should have gotten" the first time. This part is obvious but sometimes in seeing the dollars it's hard to accept paying anyone well over $250 an hour. Meet with several attorneys if you can, to get a feel for who can work best for you. Learn the details of what they'll bill for and what they won't. Will they charge to respond to a 30-second email (my DH's attorney doesn't, so as long as the question is terse and to-the-point with a short answer, no bill--his policy is to not bill for anything that will take more time to bill than to respond to). Once the case is closed will they charge to represent you if STBX is ignoring the order and needs a talking to (again, my DH's attorney will call ex's attorney when she's "misbehaving," so-to-speak, and at no charge. Of course there's a charge to go back to court or update orders, but not for this quick communication kind of scenario). How many divorce cases have they led and with what result--if family law is their focus, you won't have to pay them (in billable hours spent reading) to refresh their memory of the specifics of the laws in your state!
I certainly don't know the legal specifics of splitting a business (either in the red or the black) but my un-legal thought on it is that if he wants to continue the business on his own if you separate, it ought to be reasonable that either you split the debt -and- some reasonable expectation of future profits (like a % for the next 5 years) or he takes it in whole (including the debt). My state is not a community property state, so I'm biased and certainly being overly naive on what is "fair" on this issue. In any event, you should look into the specifics of whether your state requires equal or equitable division of debts--if equitable, there might be a fair argument for him taking most or all of the business debt, particularly if the business will become his solely.
Oh, and keep a copy of everything you can (organized) and bring it with you to every meeting/hearing/etc. They should have a copy of everything too, but they might not drag it out when they meet with you and there's no sense wasting time for them to go get a document when you can pull it out right there quick. I wouldn't have thought, but I've provided court materials during hearings before (for ex's attorney ... DH's atty is phenomenal, though his fees approach organ donation level).
Sorry this got so long. Best of luck for you and your family.
ETA - I read through your other post about the business debts and you might have another option not tied to divorce action, see http://www.irs.gov/taxtopics/tc205.html. I didn't realize some of the debt is to the IRS so the situation is a bit different there. I don't imagine a family law attorney would help you with the IRS issue, but perhaps a tax attorney could? I hope you can qualify for IRS relief, regardless. Since the IRS can hold you responsible for the whole debt, even if your divorce decree assigns some or all of the debt to him (the same as the Court cannot remove your liability upon any debt, but the IRS is the worst case scenario creditor), here is a case where you need the Order to assign consequences to him for failure to pay his share of that debt to the IRS on time (going forward). I don't know what that might mean, perhaps he owes you interest in addition to reimbursing anything you pay on his behalf (not that it's of much consequence when you don't have the funds to bail him out and he drags you through the mud with him). This is bad news because it probably means both of your credit scores are already terrible and refinancing your mortgage, even if it weren't underwater, would be difficult and/or costly. Tax liens are pretty much the worst thing that can happen to your credit rating. :-( It could even make renting difficult. I am so sorry he has hidden this from you, what an abuse of your trust. I hope it's not as bad as I'm assuming the situation to be.
Edited by autumngrey - 9/4/13 at 3:04pm