My very best advice is to buy this book and read it through several times.
http://www.amazon.com/How-Rebuild-Yo...8579225&sr=1-8
The questions you're asking tell me that you will have several hundred more questions and you may as well learn from one of the best, David Vizard. After you have digested Vizard, come back around and ask any questions here that you still don't understand. There are professional engine builders on this site who can answer everything for you.