I'll try to answer my best.
1) Canteen - I think the hype on him may be a little overblown, he's not going to be the go to WR or the star- that'll be Funchess- but Canteen had a great spring by all accounts and he's definitely going to play a lot both in the slot and outside. Canteen's footwork and routes are smooth, some have even said best on the team of all the receivers- and he's been out-shining the other frosh WR's- including Drake Harris who was an EE and was a high 4*/boderline 5* WR recruit.
2) Haven't heard much on Darboh to be honest. Jehu Chesson had a few really big plays as a rs frosh and flashed that speed. I'd be very surprised if he wasn't the fastest receiver on the team. He's also got that speed in a 6'3 frame. Canteen was a big star this spring and looks in line for a starting gig. Darboh might be odd man out.
3) Funchess at WR has more to do with Funchess being special than Butt. Funchess has always struggled blocking, he's horrible at it. He's always been more of a flex player than a real TE, and he's never been more than maybe 225- which might explain why he struggles blocking. He really should've been playing at WR from the beginning. He had an awesome spring at WR and he'll be Michigan's go to guy in the passing game. Butt had a pretty solid frosh season though, and I do expect him to figure into the passing game a lot more. He's definitely more of a true TE than Funchess and he can actually block a little bit, which should help make the offense less predictable. If Funchess was lined up in-line defenses knew he wasn't going to block, and if he was asked to block he was getting man-handled.