1) The Ranger feats rapidshot, precise shot, improved precise shot do work. Manyshot is bow only. None of the Ranger PrEs work with thrown weapons.
While Tempest and Arcane Archer do not lend themselves to Thrown weapons, I though Deepwood Sniper would have been a perfect enhancement for thrower builds.
2) Returning throwers used to not have ml: requirements. They were fixed/converted in a patch, but a very few survived with no ml:.
3) There is a separate line of feats for WF:Thrown, WS:Thrown, GrWF:Thrown, GrWS:Thrown, and ImpCrit:Thrown.
4) TWF feats do not apply (can't throw 2 weapons at a time). However, certain weapon enhancements do apply if used in offhand with thrower in mainhand. Seeker in the offhand will provide bonus to the mainhand thrown weapon.