Well OK then let me give you some guides
The Williams is by far the quickest car, but not necessarily the most fun. It and the Ferrari use semi auto too, which makes things easier.
Some of the sleepers are the Scuderia Italia, the Tyrrell and the Larrousse, a nice little car with no vices. I would love to use the Jordan more but as I sadi, it is flawed in its code sadly. It still quick but you cant really push it as it snaps away real easy.
If you have a G25/7 wheel, use the h pattern, it's so much fun, (you dont have to use the clutch, just time your blips) and try and either use the main FFB settings or get hold of real feel plugin, which suits some, I perfer RF settings on this mod, but a lot like real feel, you can select FFB settings based on real feel in the mod updates section of FFB.
As for online, most servers running this will be locked and leagues sadly.
Set up wise, things like rad opening, brake ducts are main areas. Wing settings make a big difference, but so do things like ride height and packers. I usually run a little less neg camber on the fronts and more on the rears. And gearing is vital, some cars really run out of revs on standard gearing, especially if you change wing settings. You shouldnt have to touch diffs, main suspension areas, they are pretty good default.