I think you're right, it supports Amazon and Hulu right now. I just don't use Hulu so I kind of forgot.
As for the buttons, yeah, if you just press (rather than hold down) rewind or fast forward it will jump back/forward 10 seconds, like the Roku. Well actually, it appears to do that in the video player for Amazon, Youtube, jumps in 5 second increments everytime you hit it in Crackle, and in Netflix it starts fast forwarding or rewinding (and goes faster when you hold it down). I think it jumps 10 seconds in Crunchyroll, too. So, most of the time yes, but not in Netflix, there you have to hit rewind and then hit play a second or two after.