As I said, Toast found this number. Loo at her profile, she's done over 15,000 quests. I think she's getting pretty close to the exact percentage
yes and no. its confusing. the devs made it confusing on purpose. which is also confusing. the devs work in mysterious ways. some would say they don't work at all. zing.
if i remember correctly, there is a dip in plunder until 2/3 of your lands have sos. so guilds are better for plunder unless you convert to full sos osf. but of course the stats suck. so you have to choose. i never did look into how volaries work...so you will have to ask someone else about that.
Does what regenerate? Troops? Yes. Speakers? Not on computer, everywhere else, yes. Crystals? No. Nobility? No. Gold? No. Prestige? No.