[Edi]

1) They can carry all the items they have slots for. IF different forms have different slots and the form changes from one with more slots to one with fewer, those items will either be dropped into the lab or lost. There is some peculiar behavior in some cases, most notably dragons.

2) Yes, they do, and no, there is not as far as I know. Could be there is something somewhere, perhaps in Sunray's national unit lists, but I have not made a list of spells.

3) Not unless he has the Recuperation ability (Kraken, Gorgon, a couple of others and Pangaean units have it). Otherwise you need Gift of Health, a Faery Queen or the Chalice or must play EA Ermor or Arcoscephale (any era). See the FAQ section on afflictions.