Hey there,
Just a quick note. Two characters YOU have or have created/possess can NEVER interact (unless under very specific circumstances and you get a ton of permission). However it would be easier for you, for the mods and everyone if alt pcs never met ever. So that is the general rule.
Alt_PC. Read related articles as well regarding alts.
I don't really understand the second question, but you can come across bodies in flashbacks. Flashbacks are just like normal threads in the regard that you can do most anything (as long as no rules are broken).
To find hidden things from pcs I would ask the player and run it by mod (just so they know what's up and can weigh in on individual situations). If that stuff is going to go down, I think there would have to be a lot of proof (aka threads) that person A did have the item to begin with, and that he did hide it. Then some story on how your PC (person B) comes across this hidden item.
I think I answered your questions. I'm not sure. Some of them were worded a bit odd. And I think I got all the typos from autocorrect.
“Method is more important than strength, when you wish to control your enemies. By dropping golden beads near a snake, a crow once managed to have a passer-by kill the snake for the beads.” ~ Henry Wadsworth Longfellow