My 2 year old is better behaved than my roommates 10 year old How do I deal with it?

I have a 2 year old daughter turning 3 next month. She is very well behaved except a few traits she picked up at her dads house I am trying to brake her of. The only problems I have with her are she eats very little at dinner and is very picky about what she is fed. I also have problems with getting her to go to bed as well but she is 2 and was co sleeping with me for a long time. My roommates ten year old has no respect for women. He does not listen to his mom unless she has to yell at him. He does not listen to me and if I ask him to do something he glares at me or rolls his eyes and I know I have muttered under my breath about how he is lucky he is not my child or I would smack him for giving me that look. If we take him to the store he has to sit in the cart so we can try to make sure he does not run off because he has a habit of doing so. If he is told he can not take his DS into the store he says I will just sit in the cart and his mom relents. If his dad says he has to eat all of his dinner he goes and shows his plate to his mom and she always says 2 more bites then go give the rest to the cats. For the most part if one of the guys says something he does it immediatly. The girls it takes 3 times or yelling before he does something. He is the same way at school. Last year he walked all over his female teacher this year he is well behaved for his male teacher except when it comes to lining up for recess. I have heard she thinks I am not raising my daughter with enough discipline. She said this to my fiancee not me but her son acts more like a baby than my daughter does and it drives me nuts. Soon we are supposed to sit down and discuss getting a bigger place and what if any issues people have with it and I don't know how to approach this situation because i don't know if I can deal with her son continuing to act like this without being disciplined properly for a ten year old.