Aww, poor Mave. Well, I'm no animal expert, but I do have 2 cats we've had since they were kittens so I'll try to help you as best I can.
1) It keeps meowing from the inside of the room (the cat is isolated to a bedroom since the roommates don't like the cat).
This is like "crying baby syndrome" in cats--there's nothing you can do but ignore it. It's really irritating, I know, but unless you're willing to let it roam in more than one room you have to just ignore the meows like you would a child who cries and cries and cries at night. Eventually it will go to sleep. Just make sure the litterbox/toys/food is in that room and you'll be fine.
2) It keeps scratching things and more recently, it has started to bite and scratch me.
Typical cat behavior--well, ok, not the biting. She's probably just irritated. I'm assuming you don't have a scratching post for her; that's probably the thing she needs (and to be taught to scratch ONLY on that--every time she scratches on something else take her to the post and let her scratch there, or squirt her with a water gun when she scratches anywhere else). As for making a scratch post, some carpet scraps (or an old towel) wrapped around a piece of scrap wood/poster tube should be an inexpensive alternative.
3) It keeps knocking things down, messing around with cables (it unplugged my computer once while I was working on it!), jumping onto my computer keyboard ahhh....it just gets in the way!
Yup, kitten behavior alright. There's not a whole lot to be done about knocking stuff down, except to train her NOT to get on things. Use an aforementioned squirt gun (that's how we disciplined our cats)...and for the cables, that's a little harder. If it's ok with whoever you're cat sitting for, you can buy a spray to put on your cables that makes it taste really really bitter so she'll learn not to chew on it. Some people don't like that stuff though so you probably need to check first if it's ok. You can find it at most pet stores.
I don't know whether the cat constantly needs attention 24/7 but I can't give that to him! I generally have a 9 to 5 work schedule and I have my own life! I don't have the time and patience to pick the cat off my computer keyboard, stop it from biting up any cloth or pulling out cables.
Kittens DO need a lot of attention but you don't have to worship them 24/7. Does she have any of her own toys? Like an old sock rolled up as a ball, some string tied to a doornob, anything like that? If you can't entertain her, perhaps there's some things you could give her to play with by herself.
I'm so stressed out with it, I finally burst into tears today. I've never taken care of a cat before and I don't know how to deal with its habits. I'm starting to get frustrated and impatient with it and have been tempted so many times to take out my anger on the cat.
Aww, poor Mave. Well, the only thing I can suggest to you is just to keep in mind it's like a baby: crying is the only way it knows how to communicate, and it's totally focused on ME. Part of your complaints are just normal kitten behaviors that just have to be grown out of. *shrug* I wish I had something better to say...perhaps taking a few minutes to play with her (like with some string or toys or something) could make you feel closer to her and create some good memories to tide you through the frustrating ones.
1) leave the lights in the room on?
2) keep the heat on the room running?
You probably don't need to keep the lights on (cats have excellent eyesight) but the heat is probably not a bad idea, especially for a kitten.