Aolive - Just wanted to get back to you real quick about a few thoughts I had and what ended up working (or not) for us. My DD1 was my high-needs, boob loving baby, so when I was pregnant with DS I just assumed that I would tandem nurse them until DD was ready to wean. I went through the drop and stopping of the milk supply for a few months, and DD kept nursing through it all. The worst time was really the several months of feeling like I could not stand to be touched (much less have a nursing toddler) - that nails on chalkboard feeling that some moms talk about? I had it BAD, but we plodded through it eventually. We did not night wean, and we kept a family bed.
Ultimately, I think the experience had good and bad elements to it. On the plus side, DD helped tremendously during those first days that my milk came in - the engorgement was much, much less. It also provided for some serious bonding time between the two of them, since they often nursed at the same time - they are still very close to each other and play together all the time. Since I had a homebirth, it was easy to have DD present for most of my labor and to be able to nurse that night without being in a hospital environment.
On the negative side, it was HARD to tandem, and it was much more physically and emotionally draining for me. I couldn't have done it without the support of my DH and group of friends. I was definitely more exhausted all the time, and more sleep deprived having to nurse them both. Nursing DD also ended up becoming a power struggle between us, unfortunately. I probably wasn't consistent enough in setting limits with her, and (being the person she is) she took advantage of it.
That being said, I tandem nursed them until she was 4 years 4 months old. DS self-weaned almost a year to the day later.
As for the homebirth aspect, we planned on DD being present for labor and birth (with just the midwife and her assistant present). No other help if DD wigged out. As it turned out, she did fine for the most part, and was my sole company for much of my labor barring the last couple of hours when DH got home. We ended up calling a friend while I was in active labor to take DD for a little while since it was getting pretty intense for her (and she and DH were arguing, and I couldn't focus on the contractions). She was gone for a total of an hour, during which time my midwife arrived and I had DS.
While *my* situation ended up working out fine, I think in hindsight it would have been better to at least have an emergency plan in place, just in case something happened or DD wasn't able to deal with me being in labor. Having an extra person there for your DC just in case, is a good ide, and can take a lot of stress off *you* when you are in labor. I also would have been more proactive in finding ways for DH to take over more of the night parenting duties (as well as finding ways that *they* can bond outside of bedtime) with my older DC. Even though that wouldn't include nursing (obviously!), I think it is important for a partner (as well as the child) to find ways they can comfort/be comforted while Mama is busy. If you work on some strategies NOW, they can be in place by the time your new little one arrives. I would also set some serious boundaries with the nursing and attitude (i.e. - If you want to nurse, you have to ask politely. Scratching = no nursing), and if the boundaries are worked on now, they will be in place by the time you get your homebirth. Also, there are some really good books for kids on homebirth and getting a new sibling that might help him get used to the idea of a new sibling.
I hope that helps you figure things out! Congratulations, and I hope you have a wonderful pregnancy and homebirth!