Hi there David

welcome to Madmodder.
About setting the tool height at centre with a laser, thinking about it, it might work, but some of the laser pointers I've come across have a fairly wide beam, ie 1mm or more. Also you would have to make sure that the tailstock was in allignment each time you used that method.
The method I've found to be quick and easy is to gently trap a 6" engineers rule ( or even better a 12" rule ) between the tool and the workpiece. If the rule is exactly vertical then the tool is set on center. It may not be exactly on center, but it is close enough and when taking a facing cut you will be able to finely adjust it to perfectly spot on centre.
Tim