OK, this definitely seems like a simple task but it's killing me...
What's the easiest way (or is there a nifty tool) for 1. unclipping the upstream sensors and 2. loosening these damn things.
Got both downstreams done, but the upstreams...

 

Run the engine to operation temp, the O2's will come right out.
No tips are unplugging them.

 

The best way I found was to use 2 hands. One to press the clip, and then one to pull the wire of the sensor. You can also try some PB blaster if it is too ridiculous, same goes for wrenching it out of the exhaust. Takes a 7/8 wrench I believe.