Welcome! :-) The more the merrier.

For the leather, I'd look around for a good car upholstery shop. I hear they can work wonders. Then get some seat covers on it. May not look as cool, but when you want to show it off more they come off, and it will keep the original seats looking cool for a whole lot longer. Wet Okole (see another post I made last night for link) makes some really stand-out ones, but they are expensive.

For scuffs on plastic, get a high quality plastic polish like Meguiar's. I just had mine off-raoding a couple of weeks ago and had just a few minor battle scars on the plastic part of one of the side mirrors. Polish took it right out. This also vastly improved the look of my headlights, which were a little scuffed-looking when I got it.

For mud... well, I'm still getting rid of it from two weeks ago. You may never get it all. Get up under it, use lots and lots of water and a good scrub brush. Use a high pressure stream where it is safe to do so, but be careful around sensitive electrical parts and use a low pressure stream when necessary. Don't blast the front grill area with a strong stream of water - you may bend the radiator fins. Don't get anything wet that you shouldn't, like the alternator (which is mounted low), for example. Took mine through some mud pits and learned that one. :-) Especially make sure to get mud rinsed out of the brake components real good. Mud is fun, but the cleanup afterward may never end. I thing I've got it out of my system now. :-)