If you are going to quilt the quilt yourself, the backing needs to be about 2" in all directions, or 4" on both dimensions. If you are going to send it out to be quilted, the long arm quilter normally wants more than that, at least 3" on a side.
The batting size is normally inbetween the top and batting dimensions, like a wedding cake.
The crinkly look can come from the fabric, but the majority from the cotton in the batting. A 100% cotton or wool will give you the most shrinkage. The batting packaging will tell you what percent shrinkage to expect. It also provides valuable information on how closely you need to quilt or tie to secure.
Never wash a quilt top before the quilt is totally done. If you'd like to join the fray on pre washing uncut fabric, just use the search function on this board. Lots of pros and cons.
Regarding the running of the colors, at this point you are just going to have to try it and see. You can use color catchers if you have a top loader. There is also a production called Synthrapol that will keep any shed dye suspended in the water and not deposited on the other fabrics. This also needs a lot of water. Not a front loader type product. If you are worried, you can wet a piece of scrap fabric and rub it on a piece of white fabric to see if there is any transfer.