Hi Serenity,
we just started his transition with DS last week. It is actually going OK. I have the crib and twin bed in his room, but we have not used teh crib once since we began. I just felt better knowing I could offer that option if things go crazy.
We talked about big boy beds with Sam a ton before we actually made the transition. We tried to get him excited about it. We also made his BBB a car theme--which he loves---so it's exciting if I ask him if he wants to go night night in his BBB with the cars. ALthough it has been good so far, I am realistic that things could still take a turn for the worst (probably this week when DH is out of town). It sounds like your expectations are realistic as well, so that will help, IMO.
As far as going itno his room..........I don't know--we don't have that part down to a science yet. Sometimes we go in a few times, to remind him it's night night and he should get in bed; and sometimes we get sick of it and as long as he doesn't need anyhting from us (reassurance, etc.) we'll let him be--in that case, he typically climbs into bed after 10 min or so of "exploring" and goes to sleep.
I hope that helps, good luck!!! I know I was nervous!!