I follow a strict rule of ASOCT (Always sh1t on company time) and the bathrooms across from my office are shared by about 600 aircraft employees that don't shower - so here goes my bathroom etiquette.
1. Fuq putting toilet paper down, I carry a miniature sized bottle of lysol with me if I have to take a sht.

It's a must.
2. I love farting while I'm at the urinal, and I usually laugh at myself afterwards.
3. It depends on who is in there when I'm about to take a dump whether I just take care of business or go to the bigger bathroom about 100 yards away. If it's someone in business casual & I don't know them - I usually just stand at a urinal until they leave. If it's someone wearing jeans/tshirt/etc, They're some factory worker or someone from my office so I go for it and usually take something to read.
4. I eat a lot of meat; courtesy flushing is not only a necessity for everyone else, but usually myself as well.
5. Wash hands then grab an extra paper towel to open the door with so I don't touch the door knob after some slob didn't wash his hands.