1. I know this line can cut your fingers. Is it also bad for cut your rod guides and bail?
It depends on your guides. It can cut a groove in some of the cheaper guides. Titanium will probably not groove, but ceramic may.
2. When I snag the bottom with mono line I can tighten my drag and tug the line so it breaks near the lure. That way I don't lose much line or leave a hazard to
birds. Can you do this with spider line, or must you t cut the line near the rod?
No. You usually have to throw the whole rod and reel into the water and use another one:-). Actually, I've found that the spiderwire breaks down quickly when exposed to salt wand sun, so you'll probably have no problem breaking it. In fact, you'll have a
harder time trying to keep you lures attached to it!
3. Do you fill your whole reel with spider line (which seems expensive) or do you use backing?
Soem people use mono for a backing, but the spectra can dig into the mono and cause snarls.
Finally, is there a best brand to use?
Yes, Mono.