New goldfish tank questions

Hello all
I have adopted 3 fancy goldfish(1 Gold fantail, 1 Calico Fantail and a black moor) They were given to me with a 10 gallon tank, Currently the largest one is only about 2 ½” long. The guy told me that the fish were bought less then a year ago.
I have found a good deal on a 37 gallon tank and a currently doing a fishless cycle, the tank should be ready in a week or two. On the 37 gallon I have an Aqua Clear 70 that moves 300 gph, and a full bubble wall for aeration.
My questions to you are;
Is this enough filtration for the tank?
Is this tank big enough for 3 fancy goldfish?
And if it is big enough do you think that I could get away with a small school of 6 white cloud minnows?

Thank you for any advice.