As an example of what the possibilities may be, this page seems to sum it up nicely for New Jersey - http://www.divorcenet.com/states/new_jersey/may_I_reopen_my_divorce_case (completely arbitrary state selection there). I have no personal or close experience on that front. My state almost never orders spousal maintenance (requires a minimum marriage of 10 years and even then, a good argument). None of my friends have ever gotten it. One friend's ex, a SAHM who intended to SAH with the 2 kids post-divorce, tried and was quickly dismissed because they were only married for 6 years. As has been said before, move quickly--I don't imagine your right to request an extension of spousal support would exceed the duration of the order for spousal support itself, if it can be extended at all. The copy of the judgment you received from the court (request one from the court clerk if you don't know where it is anymore) may give some insight as to the option of modifying the spousal support order, perhaps even saying something like "EX shall pay N dollars for one year unless otherwise modified.
In any event, the court maintains continuing jurisdiction over the child support (and child custody) issue (you can't waive the court's authority on this issue even if the agreement said it can't be modified ever). While the amount of evidence required varies by state, a common standard is that you can motion the court to modify ("amend") the child support portion of the judgment at any time if a material (sometimes called "substantial") change in circumstances has occurred. This might mean a significant change in income (10-30%), a significant change in the children's needs that could not have been foreseen at the time of the judgment or last amendment (child care!), or a major change in the parenting schedule ("visitation" or "custody") that has been sustained for 6 months to a year (varies by state). If the circumstances indicate that child support should be adjusted, this should be straightforward (i.e. lower legal cost than arguing for continued spousal maintenance if your state doesn't usually modify awards post-judgment) way to get additional financial help for raising your children. The requirements for requesting the court to consider modification of the child support amount without a material change in circumstances varies by state--mine requires over a year to have elapsed since the judgment/last amendment and I've heard of others that require 3 years to pass.
Many (maybe even all?) states expect the non-custodial parent to contribute to child care expenses, usually above and beyond the basic child support amount. I assume your divorce agreement didn't address the issue (or at least didn't assign responsibility to pay for child care expenses) under the assumption that free care would be available for you to work. The circumstance has changed--free child care is no longer available.The judgment needs to be modified to consider the change of circumstances. In particular, if having help on the child care front would enable you to become self-sufficient, this is a good modification to pursue. If you were the obligor I would advise "don't get your child care contribution built into the child support amount owed" because you'd have to go back to court to get it removed when the kids don't go to daycare anymore!" but as the obligee, I say "get it in the child support amount owed so the state can withhold that too." :-)
I'm not personally aware of a state that orders the NCP to pay 30% of income for two children (close to, but 27-29% is the highest I personally have heard of--my state is nearly 20%). This is not to say that you're "lucky" or anything of the sort--perhaps you're even just rounding--but I would verify that it is for sure your state's current standard guideline before you open the can of worms. It would be incredibly unfortunate if this would backfire and make the situation worse by discovering he's paying 30% and the statutory amount is only 25%, for example.