I had 3 under 2 at one point.
I think with a supportive partner and/or support system, you can do just about anything. You can't always guarantee personality though. I freely admit that all 3 of my kids are very mellow. So even though it was hard, it wasn't as hard as it could've been. And my DH works at home and is an equal co-parent.
As for nursing, sure, you can nurse both, bring out special fun boxed that the older kid only gets while you're nursing, ect. Co-sleeping might be a bit more tricky--but only in the sense that you migh consider getting a bigger bed or putting it lower on the ground, since you don't want to put the toddler next to the baby at night. We had all three in bed with us every now and then, but my girl was already transitioning to her own bed by the time the guys were born.
As for nursing to sleep, that's fine. But your partner might need to take a more active role in putting the toddler down (something you should start before the baby's born). And you have to think creatively, because it won't be the same as when you just have one baby. This babe might have to learn to nurse to sleep in a sling, ect.
The toughest part is not the logistics, but the mentality you have to get over inside your head. You have to be prepared to handle one of your kids crying sometimes, because you can't be two places at once. You might (depending on how things went with your first) get taken down a notch as you realize that sometimes there are functional uses for things like 'baby buckets' and strollers and such. I won't lie to you--the emotional drain can sometimes be exponential, not merely times two. But at the same time, the rewards are great...it's been nice having kids that are all very similar in 'level' and interests, and right now at least mine are extremely close, like a little pack.
It's hard to offer specific advice that will work always--because so much depends on personalities involved. But you just find a way. Especially when your kids are super young.
