barrell questions.

Is there a formula for the proper twist for a particular caliber? I know that a faster twist is better for heavier bullets because it stabilizes them before they exit the barrel.

Also what about the length of a barrel? Bigger isnt always better. I know certain rifle makers have a penchant for 20 inch barrels and generally dont offer a longer barrel and still shoot 1/4 moa.

What about the crown and the chamber? Do certain degree crowns favor certain cartridges?

If anyone has any ideas or comments on this, feel free to post away.
How does this all relate to benchrest shooting? What about tactical shooting? Where is the perfect balance?

Im wanting to build another .223 target gun, mabye even single shot and im looking for some idea's. It'll probably be based around a contender carbine model and if any of you are familiar with these, they are very simple and highly accurate rifles with a proper barrel. The problem is, picking the right barrel. :?:

Sorry if I'm rambling.

Spade