rfactor is a new game from ISI (same makers of F1c) that will be a lot better, and easier to mod. Rfactor should be out soon, i am thinking sometime in May or June.
SCC is the best le mans mod for F1C. thats the mod we are making our carpacks for.
i believe you can still get it at
http://www.rsdg.net
Our carpacks will work for SCC, so i encourage you to download that mod.
and as far as installing multiple mods, you can do so. nothing will get messed up.. you will be able to use both of them (or as many as you install)
i really dont know anything about new cars for PTC. best bet is to check Virtua LM's website:
http://www.virtua-lm.com/ i dont have the time to keep up on all the other mods out there.
and as far as wheels go, i have an Act Labs Force RS with a H-Pattern shifter. i really like it, but they dont make it anymore. I would suggest anything from Logitech (Momo or that PS2 GT4 wheel that can be used on the PC).. I had an old Logitech, and never had any probelems (and If i had to buy a new wheel now, i would choose logitech again)