if you decide to go with 501 STF's, make sure to try on some washed 501's as well to see if the 501 cut is for you. personally i hate the 501 cut, too high rise, too baggy legs, and i dont really like straight jeans. i'd much prefer to pick up a pair of raw or raw-looking 511's that are sized up to where they fit slim instead of skinny.
as for sizing 501's, thats easy. try on a pair that fits comfortably in the waist (not tight, but not loose either) and make sure you have 3" to 4" extra length on the inseam, because they shrink 3" to 4" in length after you hot soak them. the waist shrinks like a size or so, but stretches back out to the pre-soak size or bigger after a few wears.
shoes, this is easy, get a pair of chucks or low pro vans or some other random canvas plimsoll and you're set, they usually cost well under $50. a good pair of boots usually costs you $200 and up, and on your budget (or lack of a budget) you might want to avoid that expense until you get a steady income.