I won't lie. The first few months are brutal. Flat out brutal. But after that it gets to be so much easier! And once you get into a routine and once your new baby starts to interact more with the older one it's just awesome!!!!!
I love how my girls love each other. It's the best feeling in the world! You guys will get to the good part soon enough.
Re: The transition from one to two...
My son is the same way. When my friend had a baby, DS was SO concerned about it. If the baby cried, DS would run from their play room to pat his back or hold his bottle. It will be cute....but annoying sometimes. He's pretty good at being gentle with our dogs (100lb, 85lbs, 75lbs), but being gentle enough for a baby will be totally different!
For DD we got her the little set of baby stuff (PNP, carseat, changing pad, etc) so that when I did all of those things with the new baby, she could do all of those things with her baby. It worked awesome! We didn't give her the presents until we brought the baby home from the hospital but once she saw that she had the same stuff to use for her baby, she didn't try to do everything with the real baby.
That's so sweet! And such a great idea. Right now DD just thinks babies are animals. She goes around play group occasionally petting the younger siblings. I guess at least she's gentle!