Let me address them in order
1. If I remember correctly it is on the top of the intake manifold towards the front of the engine.
2. I would go with the 160 degree thermostat the motors tend to run cool at least mine do and if you are raw water cooled finr otherwise go with the 140.
3. Yes clean it off, get the gasket mating surface as clean as possible.
4. I do not know what you are talking about here my part number 5 on page 20 is a lock washer in my parts list. download my parts list from
http://www.apyc.org/chriscraft/files.html then let me know but I would suggest going to
http://www.marine-sales.com/ Earl has everything but some things are not cheap!
5. Yes it is.
Let me know if you need anything else
markweller AT sbcglobal.net replace the at with the correct symbol sorry the spam is getting out of control.