Very little, recently. People are important, and it's always possible to get better at whatever you're attempting. Everything else seems to be mutable.
2) Define friendship.
What kind of friendship?
The easy kind is that a friend is someone you hang out with because you have similar interests - someone you like being around.
The tough kind is that a Friend is someone you'll side with against others, just because they're a Friend. But it's also someone that you'll tell the truth to, even if they don't want to hear it. It's important that these two go together - if you don't have the first, there's no attachment, and if you don't have the second, there's no realism. Note that this makes it perfectly acceptable to defend your friend against someone else, then as soon as the other person has left, turn to them and say "but you know, they're right." (It all comes down to who's allowed to say what.) A Friend is someone you'd go incredibly out of your way for if they needed your help.
Obviously Friends are far rarer than friends.
3) You've got ten minutes (no cheating) to teach me something simple that can change my life. What's the lesson?
That the single greatest force in the universe is willpower. If you have enough willpower, you can succeed in things that would normally seem (or even be!) completely impossible. At that point, the question just becomes what you care about most to spend your energy on, and how much energy you have.
4) What gets you through the tough times?
Willpower. :P If I gave up, well . . . I'd have given up. If I don't give up, there's still a chance, no matter how slim. I might change my avenue of attack, but I won't give up.
5) You've got to spend the rest of your life in one room, any size, shape, colour, furnishings you like. What does it look like?
It's a top room in a tall building. It's about twice as long as it is wide. Two walls are entirely glass, and are angled so that the rain runs down them. The ceiling is glass too. (Motorized blinds for all of them.) It's got two floors in this single room - a balcony that's about a quarter the size of the bottom floor, in the corner furthest from the two glass walls. There's a two-meter-tall screen on the long wall, the section that the balcony isn't above. The kitchen is below the balcony, with the only overhead-mounted artificial lights in the entire room. The other non-glass-walls are covered with bookcases. Hardwood floors, with carpets. In fact, the entire room is wooden - the only metal in sight is obviously attached to technology (i.e. the screen and any appliances in the room.) There's a comfortable couch in front of the wallscreen, a table with several chairs around it between the kitchen and the nearest glass wall, and a desk with computer and chair on the balcony. The balcony is accessible via a staircase that runs up the wall that the wallscreen isn't on.
I could draw a floor plan if you'd like. ;)