1.when making a sorority what are some good tips and hints to making it successful?
I haven't played that many Greek houses. In TS2, males and females can be in the same Greek house. I guess it's like that in RL too. Make use of the pledges to write term papers and do assignments, and then have the full members party! Make sure you have underclass members when your player graduates if you want to keep the house going.
2.when making a sorority can more than 8 people live on the lot?(meaning people who pledged)
Unless you have a mod that allows more than 8 sims on to reside on a lot, no. Squinge and I both have mods that allow this, each of us with a different take, but either would work fine for you.
3.do they get better grades for woohooing with a professor?
Grade increase for woohoos with professors in your major is 5%. Nothing for the other professors though.