As for your brother. You've identified clearly that he is spoiled, is sort of a family baby, and disrepects you and to some extent, your belongings in the manner of not borrowing them responsibly, in fact, stealing from you from the sounds of it.
This is not a time to view someone as the older or younger brother, since both of you are adults, but the fact remains you are older, however cannot be an ultimate factor in find a more probable solution.
You need to sit down and have a talk with him. Let him know his flaws, and tell him that he can't keep doing the things he does towards you and others in regards of not offering respect. Then not out of anger, you gotta tell 'em how you feel and that it isn't making a good brotherhood relationship. Of course it's always good to let him borrow things, but not when you really need them.
Help him find a job.
Don't play nice all the time with him, but don't play Mr. Angry with him either. Be the boss of yourself. It will take energy to be strong, but don't let it run on your bad side. Good character comes from the art of dicipline and when to act upon certain things. It's kind of like taking your manager seriously at work, or trying to get involved in a team that doesn't like you because of your differences. But you have to make an effort, because if you don't, it will make you weaker and weaker if you keep letting things like this pass up. Like a family, you try your very best to help a sibling because you care about them. Of course it will be hard, but it is better than not trying in the first place.
Get him involved in things where high standard people are involved. Not high maintenance people, but people who are willing to correct him if he does anything wrongful or can offer feedback without being scared of offending him. Usually it's people he won't know that he may listen to more, tender or harsh, though everything must be tempered accordingly.
It's direct and indirect communication you are facing. Don't play games with your brother, be more direct and decisive when time requires. Your focus is to avoid being indirect, don't confuse him with goodplay, give him a taste of his own weapon in a different delight for offering him a chance to grow, and not condemning anyone. Obviously none of this is any more achievable than the examples you set day to day. So if you're surfing porn or something, he's really not going to take you seriously, for example. So list all your habbits, and make sure you are on top of things. Otherwise, you are just going to play recycle with him, and all your days will be the same until you do not have him in your life anymore. From the sounds of it also, I don't think he's going to change any time soon, even if he gets a girl friend - boys and girls 'usually' match up with similar ideals, I don't see a girlfriend helping in the picture, if that's what comes to mind. But if you disagree why so called "hot" girls fall for the bad boy, PM me that you've made a thread, and we'll take it from there.
Anyway, you can't avoid your brother, he's already your room mate. All you can do is teach him how to grow up like a man, and hope that he absorbs it all in time when certain aspects of reality hit him, and by all means, if those winds crush his walls, we'll know he had an ear only to let lessons go out the other, and a mindset for too much indulgence without credibility, sacrifice without reason and effort without thought. Poor brother, hopefully he loosens up his bad behavior and learns something, I'd hate to watch him get beat up by a bunch of guys with an attitude as bad as his own.