Why wasn't a Uchiha asked to control the Nine Tails during its attack?
As for the Uchiha, the nine tails was already being controlled by Tobi at the time, so I doubt anyone would be able to control him on top of that. 

Not to mention, the Uchiha weren't exactly trusted at the time, following the Second Hokage's rule. 

As for the three sannin, it wasn't explained anywhere, but it isn't hard to imagine them being at a remote mission and out of the village.