It has been forever since I have felt as if I have needed to vent and/or get advice.

Just a quick summary...
We have my SD17, my BD12, my BS9 and back again.... SS21 in the picture.
SD17 is with us every other week.
BD12 is with us every other weekend during the school year, plus school vacations and with us all summer long.
BS9 is with us 24/7.
SS21 was living with his mom 24/7 starting when he was 18 because he had a huge party at our house on a weekend that we were out of town. The place was trashed, things were missing and he didn't want to face the consequences so he ran to mommy's house and avoided his father (my DH). This was about 3 years ago.

SD17 has seemed to level off with her attitude, been more appreciative, helpful and respectful.

A couple of weeks ago, just before DH and I were going to go to bed, DH receives a call from SS21(3 yrs. later) saying that he got into a big fight with his Step-dad and mom. To avoid confrontation, SS asked if he could stay at our house to avoid confrontation. Fine, whatever. I expressed my feelings to DH about this absolutely not being a permanent situation. He's 21 and old enough to take care of himself, with the exception that he has a bad anxiety disorder. I'm no psychologist or doctor but I am convinced that it stems from SS's birth-mom being so overbearing and doing EVERYTHING for him. She is the type of mother that would still wipe his own butt if he let her.

He has been working at the same place for the last 4 1/2 years, which is great. Although, he hardly makes more than minimum wage. He only works 20-25 hours a week and wouldn't be able to support himself if he tried with that. He desperately wants to get a better job, apply for assistance to get on his feet and get his own place, or so he seems. I know that he wants to but I don't believe that he's putting as much into looking for another job, etc. as he should be.

When he's not working, he's mostly in our spare bedroom playing World of Warcraft or on the Xbox in the Family room.

When I was cleaning the house last weekend, I noticed, in the bathroom that he is currently using that there was urine all down the side of the toilet and a little on the floor. For goodness sake! The only other people who use that bathroom are SD17 and BD12. Even BS9 can make it in the toilet.

I am at the point that I am not even completely comfortable in my own home. I don't feel like I can completely relax, hang out in my pajamas or even watch TV in my own living room. I have been talking to DH about how this is making me feel and how this needs to be rectified ASAP. He has told me that I should express my feelings and speak up because this is my house too. Although, I don't feel as if this is my problem. I feel a bit insensitive to say that but, seriously, SS21 is an adult. At the rate that we are going, he is never going to move out.

I guess what it all comes down to is that I need some suggestions and a direction to go in, whether it be to leave it all in DH's hands or step in and start delegating myself.
1)What should I do and/or say?
2)Am I extremely insensitive for wanting SS21 to be on his way?
3)Should I be giving him specific responsibilities and charging him rent, even if it's only a small amount? (I know that if he goes back to his moms permanently he will be there for the rest of his life)
4) Would it be wrong of me to limit his gaming time, etc?

I'm thinking of putting together a contract of sorts with these things in it.

I can't continue to let him continue to just settle in and stay forever!

I'm confused, to be honest.