Hendelbolaf |
Pathfinder Adventure Path Subscriber; Starfinder Charter Superscriber
While it does not say feats, it seems reasonable to lump them then in with "level, class" and other such things that remain the caster's abilities and not the possessed creature's abilities.
So, I was the DM ands a sorcerer took over a fire giant but she did not have the feats to use his weapons as good as him or the base attack bonus so she stuck to casting her spells from the new body.
In the case you mention, I would say that caster would not have access to the fighter's feats unless the caster happened to have that same feat.
It seams that by natural abilities it would mean that if I used Magic Jar to take over a creature with Darkvision, then I would have Darkvision while in that body.