What gooki said.
The only thing I'd separate out anything is STRONG colors - reds and darks - as they will gunge up your lighter colors over time. But mostly, we do two piles: whites/lights and darks/reds. But I sometimes don't care, and will dump them all in as anything we've got that is red is so old that the dyes don't really leach out anymore.
I buy powdered detergent, usually Arm & Hammer or Purex depending on what is on sale, but store brands are also a good deal sometimes. Don't look at number of loads; compare weights to price to get the best deal, since the manufacturers are going to tell you to use WAY more soap than is really necessary. It is my understanding that liquid detergents mean you're paying more for water weight. Throw in the powder while the water is running and let the washer fill at least a third before adding the clothes so the powder dissolves and doesn't streak your clothes. It dissolves faster in warm water, but I use cold for energy savings, which you're not going to have to worry about, so probably you'd be good to use the warm water setting on everything.
If you have any stains, pre-treat. I do use "shout" but most of the time I've just made a paste out of the detergent with a little water and rubbed it into the stain and let it sit for an hour before I throw it in the wash. Best way to treat stains is to not get them - if you get anything on your clothes, rinse it immediately with cold water and a bit of soap - even hand soap is good to keep the stain from setting in. Wash on cold and check before throwing into the dryer as heat sets stains.
I do use borax in my wash, for really heavily soiled loads. One cup per load, and sometimes reduce the amount of soap a bit to compensate.
Don't go by the "recommended amounts." For lightly soiled clothes, I use much less soap. I never use a full scoop and usually it is under the halfway mark - too much soap and your clothes are getting clean, they're just getting choked with suds. It's usually pretty easy to figure out the minimum soap you can use and still get your clothes clean (hint: it's more about the agitation and water flow than amount of soap) This also means don't pack the washer so full that the clothes don't have room to move.
I like using the downy ball (fabric softener ball) but not with downy, tho. You can use any liquid fabric softener in there, but I use white vinegar (fill the ball up halfway) and then you don't have to remember to run back down there or hang out trying to catch the rinse cycle. The acid in white vinegar is too mild to harm fabrics, yet strong enough to dissolve the alkalies in soaps and detergents. Besides removing soap, white distilled vinegar prevents yellowing, acts as a fabric softener and static cling reducer, and attacks mold and mildew. I've rarely gotten a scent of vinegar after the clothes are dry, and that's just when I used a VERY heavy hand. Give things a good snap/shake and then hang/fold. Throw them in the dryer with a cheapy generic dryer sheet if you don't want to go the vinegar route, but you still might want to do it once a month for fabric softener/soap build-up removal.
Air drying in a dorm room is possible, but I wouldn't want to do it. You'll have damp clothes all over the room and it makes the room feel damp to me and depending on the temperature/humidity, it could take quite some time to dry. If you're only doing two loads a week, then the cost should be pretty minimal. You could also separate out the light fabrics to air dry - lightweight shirts underwear and sheets - and put the heavier fabrics like blankets and jeans into the dryer. I do imagine that having your underwear and socks strewn all over a shared area might be an interesting conversation starter, however. :D
