I see you're taking on a lot..good for you.
I'm familiar with the V8's but not much with the 6cyl. My friend has one and has done extensive work on it. You may have just a leaking valve cover gasket on the rear corner...check that first. From what I know the rear mains seals aren't issues unless someone abused the car.
The headlight lens all you need is any metal polish...any hardware store sells it. You can even use tooth paste.
The front ends wear real bad on these at 75-k I mean all the suspension arms/trust arms and ball joints. The tie rods are usually ok unless damaged like yours.
Usually speaking the 02 sensors are fine and it's a clogged or bad Cat converter. You may get lucky if you take the 02 out and try and clean them with break clean-not carb cleaner. It also may clear up with fresh fuel. Absolutely put in a gas additive of your choice and run a full tank through.
The water pumps go bad on those regularly so keep a close eye on that. Yes the coolant tanks go as well. If your A/C is not cold or your heat is warm the electric valve that controls coolant flow from the expansion tank goes bad all the time. Located on the left fender-heater control valve. I believe yours has a auxiliary pump built in and just makes it cost more. Bav Auto sells OEM or German after market
This guy does a great job on pixel repair and he does it in one day turnaround. He will email you pictures when he is done. I had the instrument cluster done, all bulbs changed, radio pixels and chrome rings around the gauges done for $300 including overnight shipping.
Best Pixel Repair for BMW, Audi, Saab, Lexus, Range Rover - Best Pixel Repair
Good luck....looks like you will have a great car when your done.