Exhaust manifold questions

Well, I have the answer to 1 of the 4 questions. The O2 sensor should be a metric 18mm x 1.5 thread pitch. Summit carries this plug:
http://www.summitracing.com/parts/SUM-G2990-1/
Our local ACE carries an oil drain plug with these same measurements, I will pick one up there, for about $3.00.

Still hoping for the answers to the other 3 questions...
C