2) when I stretch the dough on the peel, I form a slight oval that is wider (perpendicular to the handle of the peel) than it is long. Launching the pie tends to stretch it lengthwise a bit, and I end up with a nice round pie.
For a while, I was doing the same thing, but I recently discovered that, depending on how you launch the pizza, you can elongate it a bit (if it's oval) or you can leave it pretty much intact. It's hard to describe, because feel plays a part, but I'm pretty sure it's about speed. It's like pulling the tablecloth from under a table's worth of dishes. If you do it fast and have a low friction environment, the inertia of the dishes keeps them pretty much in place. With pizza, speed keeps the pizza from elongating, and, unlike the dish trick, you can get the pizza moving in the opposite direction before you do the pull and further counteract the pulling force.
This is why just about every pizzeria you come across stretches round pies and the pies stay round during the launch.
I'm not saying that the slower pull, with the slight elongation is a bad thing, but I find it gives you a bit more flexibility to have both the slow pull and the fast pull in your repertoire. That way, you can either stretch round and launch round, or, if you happen to end up with an oval, you can correct it on the launch with a slower pull.