Yes, Deidara can beat Kisame high diff, but kisame does have his counters for just about all of deid's arsenal, same as deid has his counters for kisame's.
The dots in the red circles happen to be water that separated from the water bubble so I'd have to say that he isn't exactly holding it in place and if he goes into the air, the bubble will keep on falling apart. I guess he could possibly float or something like that, however, I seriously doubt that he could actually ''fly''.
That's a summoning shark which probably doesn't have any chakra. Kisame while fused with Samehada is able to hold an entire lake together. Kisame would be capable of holding a bubble of that size together so that it wouldn't start to deteriorate.