I would personally suggest starting with overly fine paper and work your way backwards into however coarse and powerfull you can handle. Different people can work with different things. It would be better in my opinion to do this then to start overly aggressive and find yourself going "oops" to a hole through the glass.

Myself, I worked with an orbital and I think 160 paper, and a belt sander with medium grit paper.

> When sanding between coats of epoxy (filling the weave) should
> I use a random orbit sander with 100 grit paper, or is that too aggressive?
> Should I sand by hand?

Sounds to me like you cut the cloth a little to small and don't have enough extending over the chines. Yes, I'd just sand it away (that's what I did with each instance of similar problems).

> Last night I put a second layer of fiberglass on the bottom of
> the hull (just between the chines), and I had a lot of trouble with
> strands of fiberglass coming off at the edges and making a mess. What
> do other people do about this? What do I do with all of the strands
> that are now stuck to the boat right along the edge of this piece
> of fiberglass? Sand them off when I feather the layers?