-how old was your toddler when your baby was born?
DS1 was 23 months old when DS2 was born, so I barely fit in this category.
:-)
-if you had a toddler that really liked (demanded) to be held/carried, how did that work out?
DS1 likes to be carried, but doesn't get whiny about it. I have found, though, that it helps to be a bit proactive about it. If I don't wear him at some point during the day, or have another type of alone-cuddle time (like sitting on my lap while we read), he is more likely to start hitting or throwing things. Thankfully, DS2 likes and sleeps well in the stroller bassinet, so our routine is that when we walk to the playground, DS1 sits on my back one way. Also, when DS2 is sleeping, I'll sometimes ask if DS1 wants me to carry him. He will often come and ask to sit on my back (for a few minutes at a time), but he takes it nicely if I tell him he has to wait. In the beginning, I'd tandem wear them in a crisis, but I don't really do that much anymore.
-if you had a toddler that needed to be parented to sleep for naps and bedtime, how did you handle that?
Hubby took over DS1's bedtime routine during the pregnancy. Right now, he sleeps in DS1s room, and they cosleep for part of the night. DS2 sleeps with me. (It has gotten so I've completely tuned out DS1 in the night...I literally do not wake up when he needs attention. I know, it's awful, but it's because I trust DH to care for his needs, and I need every bit of sleep I can get.) In this situation, I believe that divide and conquer is the way to go, even if it means sleeping apart for a while.
Naps--DS1 sleeps best in his stroller, so in the beginning I would often jiggle the stroller while the baby rode in a sling...or take them both for a walk in the stroller. That was also the best way to get them both to sleep at the same time. Now, DS1 falls asleep on his own for naps, but that's how I did it in the beginning.
-if you had a toddler that was a hitter/scratcher, did they show agression towards the new baby?
He was not a hitter or scratcher, but after the baby came he started doing this on occasion. It seems to be more to get our attention than jealousy...at least that's how we interpret it.
-what kept you sane? 
-Having help the first couple of weeks. DH was able to take three weeks off to care for DS1 and do the housework in the beginning.
-Having excellent outdoor gear so we can get out regardless of the weather. (Last week was the first time since DS2 was three weeks old where we had a few days that we didn't go outside. When the weather reached 5F, that was just too low for us. Otherwise, we go outside every day, and I wear DS2 inside my kindercoat..) Really--going outside has saved many a day. They nap so much better when they're in the stroller too.
-Good slings and baby carriers
-A good double stroller that is comfortable enough for them to nap in
-Occasionally going on an outing with just me and the baby, while DH takes care of DS1. Really--it's amazing how going out with just one child feels like a break! (I haven't been able to go out with just DS1 yet, since DS2 is BF, so he kind of has to come along.)