The only thing that gives me pause about Rotella in the summer is the chart at the bottom of this page. He checks out on things a lot more complicated than this, so I can't just dismiss him.
http://www.dansmc.com/4stroke_oil.htm
That depends how far torn apart you had it. Usually between 2 1/4 to 2 1/2 quarts somewhere (you'll need to buy 3 quarts). Fill to midway between the low and full mark on the stick. Most of us use a normal 20-50 or 15-40 diesel oil. Spec was 20-40 but the only place that sold that was a Yamaha shop.
Here's some info on motorcycle oils if you're feeling bored and need something to read.
http://www.amsoil.com/lit/g2156.pdf
I've got a chopper with a small Sportster tank, so I use peanut oil.
Oil doesn't matter if you don't have spark................
I use the Rottela and have noticed a positive difference. Better shifting, less clutch slippage, and the valves sound a little smoother.