The pickerel is the largest of those; they get to slightly over 12" long, but 6-8" is a typical adult size. Two of those would probably be enough. The first three sunfish I named are about 4-5" long, while the others are 2-3.5" long. These last three might be the best choice- they will feed on juvenile minnows but leave the adults alone.
Yeah. Just quarantine them for a while first; a big rubbermaid tub with a filter will work. Do you have a cycled tank you can use to seed the filter media?
Expect heavy mortality from the minnows. Buy twice as many as you think you'll need.