Greg,
Lots of questions. Exactly how I was when I started not long ago. I am not a expert or even long term reloader but I will offer my thoughts to your questions:
1) Yes, I use the Lee shellholders on the RCBS hand primer.
2) TVB offers a few sizes in 38 caliber guns because there are a lot of types of revolvers in that caliber and lots of old and new as well. Lots of variables and those wanting to get the very last bit of accuracy out of their particular gun might want a slightly different sized bullet. If yo are going to be ordering from TVB, just call and talk to Jessie Clark, the owner. He will walk you through it and help you decide what you need. Personally, I have yet to go wrong with .358 sized bullets for 38 special and 357 mag.
3) Yes, I believe this is correct. It is the same principle where people load 38 special loads using 357 brass because they don't want the carbon ring that comes from shooting the shorter cartridge in the cylinder. I hope others will chime in on this one though.
4&5) I have no clue. Sorry.

I know Jess can help you with this also.
Good luck.