@gizmo350
You won't be able to run OS4 on a Blizzard 1260. Only the BlizzardPPC, and that's when/if it's released.
The web browsing experience on an AGA Amiga is slightly worse than it is on a PPC Amiga which is pretty horrible itself.
What graphics difference do you see in OS3.5 and OS3.9?
Everything you mention can be done* (to some extent), but don't expect anything to be as easy or as compatible as a modern computer. :-(
* Although, I don't know what you mean by Adobe. If you mean PDF viewing, then yes it can be done. If it's something else then it probably can't.