If you want mods, you could probably find recommendations over at SWBFgamers.com. I used to frequent it before SPUF, it's a nice community that'll help you out. They've also got servers set up on Gameranger (I think) for both Battlefront and Battlefront II, so you can satisfy your multiplayer cravings if you so wish.
As for Clone Wars (I'm assuming it's the Tartarovsky series you're talking about), I've heard a lot of people say to treat it like a highly dramatized version of what actually happened. Like the story with Mace Windu beating up the army-if you picture it from the POV of the kid retelling it to his friends, it becomes kinda plausible. "And then he lost his lightsaber but it was ok cuz he just used the force and BOOOM he killed like 500 droids and then he tore the rest apart with his bare hands and then he jumped like 3 miles and landed RIGHT NEXT TO ME GUYS". Just watch the series and picture a kid telling his friends what happened, or a grizzled clone talking about it later that night to his drinking buddies.
Grievous, however, is in my mind the greatest bad thing to happen in Episode III. In both the Clone Wars and the later version of the Clone Wars, he's an unmitigated badass. In the later version he does run away quite a bit, but he generally leaves a trail of carnage and broken body parts as he does so. He got hit HARD with the nerfhammer when they brought him to the big screen.