What is there to know about renting a room? (apartment, house, neighbors)

[ValueAddedWorker]

I've started looking for a room to rent in the same neighborhood I'm in now or somewhere close by. The plan is to rent a room that will hopefully be quieter, has respectful neighbors. It will be expensive to have my current apartment and that room at the same time, but allow me to enjoy the benefits of both places when I want.
I've already responded to a few ads but I wonder what entails due diligence when deciding to rent a room in someone's house or apartment, what to expect, how to get along with future room mates, etc. I guess situations differ, but having some pointers on the initial steps from people who've been there done that would be useful.

For example, when you meet for the first time, what kinds of questions would you ask?
i.e.
1) What's their work schedule?
2) When do they like to get up and go to bed?
3) Do they like throwing parties now and then or have friends over?
4) Why are they looking for a room mate?
5) How are household chores split?
6) Do we do our own cooking and food shopping or do we share?

Stuff like that. Besides these questions, what are some of the pitfalls of renting a room that people should be wary of? I suppose I could ask for references...but one thing you don't know when going to live with others is whether they're psychotic, so how can you be sure the situation you're putting yourself in is safe? I guess a lock on the bedroom door would be one way to increase security. Otherwise it seems like you're putting your fate in a stranger's hands.

[STT Resident]

Your post is very confusing. Why do you want to maintain two living spaces - your apartment AND a room? What are "the benefits" you refer to? If you have problems in your current apartment then finding a rooming situation will surely only double the problems. It doesn't make sense.