I know nothing about how sweet cherries grow in western PA. However since you mention you want a "small" tree/bush, you might want to look at what Raintree Nursery offers on G3 rootstock. Sweet cherries are notorious for growing very tall so what rootstock they are on will help. Some use Colt, others one of the new Krymsk rootstocks. I would think G3 would be the smallest unless someone has experience with the dwarfness and hardiness of something on a Zaiger rootstock.

I have tried growing sweet cherries on G5 rootstock. They do indeed bear while very young. My harsh winters have not been so kind on them and if we hit -15 or colder I get some or total dieback (SE WI).

Most sweet cherries need to be cross pollinated but a few varieties exist that are self pollinating (White Gold, Black Gold, Lapins, ect).