Where exactly were you mixing integers and floats? In my experience it doesn't come up too often, and if it does (e.g. writing area = 2 * pi * r) you'd be better served changing the 2 to 2.0.
round (fromIntegral x / fromIntegral y)
round is one of several functions that transform numbers to integers.
Prelude> 5 `div` 2
2
Haskell's doing the right thing here by having a separate function for integer division. It makes no sense to overload / to mean both regular and integer division.