Unfortunately I can't really answer any of those with actual experience.
But, I'd assume Vet Rez will summon all, and return experience from shroud form. Altho shrouded xp lost is very minimal ... from experience, shrouding down 20-30 levels, multiple deaths are not even noticeable on unshrouded xp, even before getting any rezzes on them. I'm sure you'd notice it if shroud was less than 5 levels lower than the unshrouded level however.
My guess on corpses, is they just disappear now, when rez timer is up. I haven't let any rot yet tho since the change, or have I? Maybe I have, but if so, it was on a toon that is already bugged, with a non-lootable corpse in Shadowrest .. can summon it, but can't loot, and there is nothing on it, since it was due to crashing (server or zone crash, I forget) on death, and even tho the DB updated with corpse, it rolled back the toon, to just prior to the death, so the corpse didn't have anythign on it, and couldn't be looted. If I think about it, I'll let some corpse rot and see what happens (One of the toons that don't have that bug, as 2 of them do :( ).
Conning corpses, shows that corpse rot and rez timer are the same now, so as soon as it can't be rezzed, it will rot. I assume it just completely rots if nothign is on it, which shoudl always be the case, as that is how it worked previously .. empty corpses didn't go to Shadowrest, they just dissipated.
Hopefully this is helpful, even if no actual experience, to the specific details of your questions.
Yther Ore.