what ever you choose to mark with needs to be tested on your project- not every marker comes out every time- each project is different-
the water soluble markers for quilters are blue- and the ink disappears when spritzed with water-
if you choose to use crayola washable markers you need to test first to make sure it does in fact wash out- and as for your other questions-
wash your quilt AFTER binding- you will be very disappointed if you try to do it before binding-
and as for water temperature- that would depend on the quilt itself- and the batting used-
is the fabrics ones that can handle hot water? is the batting going to be ok in hot water?
test--and see===before marking an actual quilt---make a small sandwich with your materials- mark it- quilt it- and wash it-see how it goes- better to ruin a 12" square than a whole quilt
ive tried many different products over the years- for me i have the best results from a good ole pencil...but i still test each time to make sure it's going to come out before marking alot-i also use chalk at times-usually if i'm marking as i go along-so the quilt is loaded on the frame- chalk is easier than a pencil then.
ALWAYS TEST