One thing Lisa and I agree on is that you'll get as many opinions on pre-washing as you'll find people who read your post :)
Unlike Lisa, I'm a dedicated pre-washer. Fabric walks into my house and directly to the laundry room. There is not a single piece of fabric in my stash that has not seen the inside of a washing machine. But ... that's me and there are lots of varied opinions on the subject, all of them right!!
I always use detergent, but not the full amount. The reason I use detergent is to remove the chemicals that were used in the manufacture process.
I almost always use Hot water as well to promote the most bleed and the most shrinkage. The reason is that if it's going to bleed/shrink I'd rather have it all happen now than later. With a few exceptions, I'll wash like colors together.
When I wash in the machine I use a hand wash or gentle cycle as a high degree of agitation is not necessary (it's not soiled), and the less it agitates the less fray it will create.
I wash most of my batiks by hand in the kitchen sink, especially reds. Reason being is that batiks typically bleed more than printed cotton, and I can see the amount of bleed and know when I should continue to wash more and more. My reds are always washed twice, sometimes three times. Some purples as well.
I had been using the "Shout Dye Grabber" and I can say that I haven't had any problems with it. I am nearing the 30 use mark though, so I picked up some of the other brand (color catcher? can't remember and I'm not at home).