Clyne is a right back, but I agree he is Man Utd quality, he's young, he's cheap, he's a model professional, has plenty of pace, definitley a case for future England right back in Clyne. He'd be a good signing, and give us good options at right back with Rafa, Jones and Smalls.
Kagawa is a fantastic signing, he will walk straight into my fantast football team, he will allow us to play a 4.2.3.1 or a 4.3.3, and can slot behind the striker or on either wing, I predict he will light up Old Trafford, he has fantastic work rate, skill, technique, speed, passing ability, he can score, he can create, he will make Hazard look like a chump.
Tiote I also agree will be a good signing for us, but I don't see it happening. The Toon are very clever, they'd want £15 million at least for Tiote, a bit expensive for us maybe, also he's African, and I'm never comfortable with the fact these guys go off for the African Cup every two years, it's not ideal really, fantastic player though.
Powell also would be a top signing, but he'd probably need to be loaned out for a year or two before he's ready to slog it out in the Utd team, excellent potential and a must signing.
Finally, you didn't mention him, but Baines is the man we need for left back.