Wow, you are fearless when it comes to color. I think it will be stunning. If you just bought small pieces, I'd put them in the kitchen sink, one at a time in a little warm water and small amount of detergent. Swish them a bit and see if any color runs out. Keep swishing and changing water until you get no more color. I'd do two of the darker fabrics. If they don't lose any color, I'd trust the lot of them. Rinse and hang to dry. Don't use the dryer, it will fray all of the edges. There is a product called "color catcher" or something like that sold in the laundry aisle at the grocery store. It is supposed to absorb any extra color in a wash load, but if you have a really light background, it would be a shame to ruin it. Fabrics that are hung to dry, are usually pretty stiff and may not require starch as you iron them. Part of the batik process is that they boil the fabric to remove the wax resist. It shouldn't shrink much, at least. Please post results.