Airhead exhaust question

[Gravytrain]

My new to me '95 R100GS has two exhaust leaks that I would like to address.
I would like to have the new parts before I tear it apart.

Questions:
[IMG]
One leak is at the exhaust pipe nut.
Do I need both 12. clamp ring and 13. compression ring?

Also, I need gasket 8.
Is there a part at the parts store or exhaust shop to sub for this that is not 13 dollars?

I hope this effort to be prepared will not jinx me with my exhaust pipe nuts.