Shower trap placement

[Lyle H]

1. I am installing a linear drain in my shower remodel. There is about 2 feet between the side outlet on the linear drain and the cast iron drain inlet hub, with a height difference of about 4 inches. Does it matter where I install the trap? Closer to the drain inlet hub or to the linear drain outlet. It would be a lot easier right at the drain inlet hub. And by putting it there it would be about a foot from the vent.
2. What is the trick to installing a 2 inch Fernco hub seal? I have tried everything.