I'm an advocate of summer pruning but not necessarily on such a young tree. Even the watersprouts (maybe especially the watersprouts) are going to help the tree grow root and wood and accelerate the time it takes for your tree to become the size you want it.

Of course, it all depends on the rootstock and since you've described vigorous growth I'm assuming it's M7 or up that we are talking about. If this assumption is correct then it would be expected that you'd loose the first round of fruitletts. They probably never set because the tree is not quite mature enough. M7 usually takes at least 4 years to begin bearing fruit, depending on variety. I think Cortlandt might take 5.

For all i know, it could be a seedling rootstock. It was only marked as "semidwarf", so i'm not sure. It seems to want to grow big! This was before i knew better then to buy things that don't say what they are.

Not many commercial nurseries in the states produce seedling rooted trees anymore but Cortlandt is a pretty vigorous variety on semi-standard rootstock. The most common RS is M7. If you get a lot of suckers at the base and it doesn't anchor real well at first it's probably that. However up in Wisconsin who knows? I'm sure they like a vigorous tree up there, especially for people not in the Wisconsin banana belt like you (I'm assuming Z5 is warm for WI).