I'm trying to teach myself/get the hang of tray development to increase my versatility in the darkroom and to be an overall better person. However, I'd like a couple of clarifications:

1) I'm used to either intermittent agitation of a tank or rotary agitation in a drum. But with a stack of sheets in a tray, you have a stack that you shuffle. If you have a stack of, say, 8 negatives in the developer, and you want to stick to the old "10 seconds per minute" agitation guideline, should you complete a shuffle of all eight negatives in each minute, or simply shift one sheet every minute?

2) My first bumbling effort in the tray (with some T-max 400) actually yielded some decent results, but I noticed some small scratches on virtually every frame after further inspecting them. I'm thinking that perhaps my method of either grabbing the sheets or moving them during shuffling might have contributed to this. Does anyone have tips as to grab the bottom sheet with a minimal risk of scratches? Of course, any other anti-scratch tips are welcome