Hi Wayne,1) Doesn't particularly matter, 80" is fine if that's easiest. Gives you plenty of room to work near the foundation.
2) Your third to last photo, it's the elbow on the left? It's supposed to be a LT90, the quarter bend is not ok as far as code compliance. No opinion on whether it will perform OK.
It's hard to see what's going there, what's the obstruction to a LT 90? That's the end of the girder on the right, your floor penetration happens to line up with the girder? What's the piece of wood at the top left, and why can't you notch it a little? Or move your floor penetration to be just next to the girder and point a LT90 outlet directly alongside the girder?
3) Double san-tees are not allowed there, you need a double fixture fitting. See UPC 706.2 at the link I posted earlier.
1) Thank you!
2) Yes, the elbow on the upper left. The obstruction is the wood and concrete part of the foundation directly below it. I could maybe cut some of the wood out and it would still fit but very hesitant to cut into the concrete. I would maybe be able to squeeze the LT 90 on but would be somewhat hard to make sure that it was fully in the 2" pipe.
3) Thank you!