craftgrrl | dying fabrics...(is it almost halloween already?? D: )

i'm one of those moms who hates buying costumes for halloween & i usually make them for all 3 of my kids. the oldest is no problem this year: he wants to be the Phantom of the Opera xD i can reuse vampire capes & make him a mask out of felt. The youngest is going to be Pippi Longstocking - again not much of a problem. the middle kid, however, is causing a bit of an issue.

i plan on making him a mummy costume (no TP involved...lol) by buying super cheap white fabric & dying it to more of a tan-ish color using coffee or tea. so far so good.

the questions i have, however are this:
-should i cut & wash the fabric (to fray it - thinking about using my pinking shears for this part or just ripping it) before washing it so the dye doesn't wash out?
-how exactly DO you dye with tea and/or coffee? just let it soak? can you keep it from rinsing out?
-are there any other (cheap) ways of getting the aged/antiqued look that i want for the fabric?
-lastly, where the hell am i going to find REALLY cheap white fabric? all the walmarts around me have stopped carrying fabric (SOB!)