B/S/T Questions

[Hankphenom]

After putting it off for years, I've decided it's time for me to clear out the closets of long-neglected memorabilia, a sizeable assortment from my days as a collector, show dealer, and descendant of a baseball legend. I've perused the Net54 B/S/T for years, and might have even bought a thing or two there, long admiring the concept of a marketplace free of a middleman and the fees associated therewith in a forum frequented by the most active and knowledgeable collectors. For that and other reasons, I would like to at least give it a try for my stuff, but I have several practical questions before I jump in:
1) I'm not set up to take credit cards, but do have a PayPal account. Together with accepting checks, are those adequate payment options for most collectors?
2) I've seen threads that discuss listing multiple items in a single post rather than individually. Any advice on that either from a sales or etiquette standpoint?
3) What's the best method of mailing items of value: signature required, delivery confirmation, insurance, etc.?
4) Best place to buy shipping supplies. I feel like going to my neighbors and telling them to bring me their boxes on recycling day!
Any other advice would be most appreciated. Stay safe, everyone, and thanks!