1. Powersteering bolts love to come loose on these cars. Sometimes its just from excessive vibration (bad mounts) or just cause they like to come loose.............. I check them periodically.
2. Clean the leads forom that starter.
3. You should be able to pick up the 'tunnel brace' from any parts car. Not so much a brace but a support if the torque tube would like to fall. Similar to what you would find in mustangs as f-bodies to keep the driveshafts from falling if you snapped them.
4. IF yours is an 85/2 (updated dash). The studs underneath the car are for the underbody skirts found on the turbo. So you should have quite a few empty studs.
5. It will run fine without the o2 sensor......... so its up to you if you want to replace it.
6. Extra wires can be yanked. They are either after market stereo, alarm, whatever......... follow them and remove them.
7. see 6
8. Ouch ...car seems well taken cared of.
9. Cut oil pressure sender wires.... nice. Should be an easy fix.
10. Uhmmm not sure why anyone would..... Unless they were trying to troubleshooting a battery draw.
11. You are driving this car sideways......... in the condition that it is............ ???
Go through all your grounds.... and clean them up.