How to questions about stringers

[Shrek]

I've read a ton of rebuild threads and lurked a bunch on classic seacraft, but I still have a few questions regarding the basics of stringers, how they work, and some of the myths that I've heard that I just cannot believe are fact. Can anyone answer the following:

1. Can a stringer be hollow and still do the job. If so, why fill the thing with AB foam? If the wood in my stringers is rotten but the lamination of the glass to the hull is good, is the problem critical or can the boat be used for another season?

2. I have heard that you need to bed the stringer or the core material in some type of bedding compound in order to prevent "hard spots." Is this true and if so, what the heck is a hard spot and why is it bad. How do I avoid this failure?

3. Can I pre-make glass stringer sections and just bond them to the hull or will doing this create hard spots? If I do it this way with pre-made sections of stringer, do I need to glass the inside of the pre-made section to the hull?

4. If I create a stringer grid, will that help the boat in terms of stiffness or do I risk more of the dreaded hard spots?

5. If I do go with the pre-made stringer sections which would be hollow when finished, do I need to glass some kind of wood firing strip to the tops of the stringers/grid system so that I have something to screw the deck to?

As always, thanks in advance.