Advice Needed: Toddler & Newborn Sharing a Room

I would love to hear your advice (whether personal or by observing someone you know)...

Since we are in a two bedroom apartment we will need to have our toddler (who will be 2 1/2 when baby comes) and newborn share a room.

I have never been opposed with kids sharing rooms, but I don't have any close friends that do this. So I haven't seen it done yet.

Would LOVE to hear how you make it work!

Specifically:
-How long did you keep the newborn with you?
-How did you transition both the toddler and the baby to sharing rooms?
-When did you change the toddler's room (how long before baby comes)?
-Did you keep your toddler in crib or transition to bed before baby came?
-What did you do about different nap schedules?
-How do they not wake each other up?

My two biggest concerns/dilemas are:
1. Karis is a crazy good sleeper (12 hour each night at least and one 3 1/2 hour nap each day)... really don't want to mess that up. Don't expect next to sleep as good, but hoping for it!
2. Karis' room is also her play room. Our living area is rather small, so most all of her toys and such are in her room. Not sure how that will work since baby will have a morning nap for at least a year when Karis won't be napping.

Alright, so exited to hear your tips!