I am not one of the experts on here but I can try to regurgitate some of what I've learned on my own and on here:

In regards to the metal coolant elbows, I think you just need to ensure that the surfaces the O-rings are seating against are clean (in the engine). I used a green scrub pad or steel wool to make sure and built up coolant residue was removed. When reinstalling your metal coolant elbows, apply coolant to the O-rings to make sure they slip into place without rolling or bunching. I think some have applied rtv and had success. There are a write-ups floating around with more detail.

There are write-ups available for the Lower Intake Manifold (LIM) gasket replacement. I've never done it but it sounds very doable.

I think turning the wheel at slow speeds draws a lot of power - I experience this vibration too.

My best guess for your low temp clunk would be strut mounts. Before I replaced all my suspension last year, it would get very noisy with clunks and bangs when it was really cold.

Hopefully some of the more knowledgeable characters will chime in.