1. Decent third party from what I've been hinted at Not amazing, but decent!
2. Depends on what they want :p
3. Based on the leaks, it depends on the developer. The developer can make it run as well as when docked if they do so wish.
Thing is, IGN's PlayStation podcast had a thing about Switch and Brian said the Switch being 1080p was a bad thing.
I'll start caring about 4k gaming after developers can actually manage solid 1080p60/1080p30 rendered games