Oh yes. Failure to properly bleed off all the air from your coolant lines can cause air pockets that result in a cracked head or failed waterpump. A Boxster is far more difficult to do than a typical Chevy/Toyota motor. The best way is with a vacuum bleeder. Here is the Pedro simplified method that I used.
Yes, do bleed the coolant. I did those exact procedures when I had to replace a cracked radiator. You may want to have an assistant handy; I got a helper to hold the rpms for me.