What size hose for thermostat bypass
 

I currently have a crossover and no thermostat. I would like to add a thermostat and bypass hose.

1. What size hose(s) do you use and still feed enough water to headers to keep cool.
2. What size hole and how many in thermostat to eliminate steam pockets when thermostat is closed.
3. Is a bypass spring valve needed (like the ones at Rexmarine). http://www.rexmar.com/page160.html


Thanks
Rick