If you have to ask you need to get a chiltons repair manual at the library to help you out or take it to a mechanic.
Check your timing. Is it possible your timing chain has jumped a tooth?
yes it will
Yes.
Info at this site might be helpful. http://www.justanswer.com/questions/2zzo6-timing-a-1966-pontiac-gto-389-with-tri-power-what-is-the-best
Images for 1966 GTO are available on the Ultimate GTO website. Ultimate GTO has a tool which allows you to search for certain pictures, narrowing down the color and other details.
Oldsmobile V8/1962 TO 1977
206.4 inches.
No
The standard tire size for a '66 GTO is 7.75x14.
no
Pontiac gto
not as far as I know.