My first answer - will be a question.. are you going to bracket race?
In regards to question 2, I will disagree with your friends approach, shutting off the pump to gain less than 10 per cent horse power ( and then heating the block / heads to different temps each run ) this is no way to create consistency!

imho, run a stock type pump with a 180 or 185 high quality thermostat, not some cheapy 2 or 3 dollar piece from NAPA either! In this way each run will have the motor at the same temp range. The water pump uses minimal horsepower but will allow you to build the consistancy you seek

Removing variables that can change is the key to consistency, keep a log book with data from each run. air temp, humidity, altitude, tire pressure, etc. etc.

Most of all , have fun with it! LOL.