Bill,
In a previous lifetime I made some heatpipes, still remember some of the design issues. But first, answers to your questions.
How critical is the 8ml and the volume in the pipe.?
Both can be changed without problems, leave about 1/3 of the bulb on the end empty.
How critical is it that all the air is out of the pipe.?
With air in the pipe it will not function, or very poorly.
If all is successfull what temperature will the hot end attain.?
The boiling temperature of the "working fluid".
A little explanation of heat pipes.
The "bulb" at the end is like a kettle or boiler, provides "working fluid" and a place to deposit heat.
The "tube" simply carries the heated
vapor to the cold end, and back again as a liquid.
The "bulb" must be at the lowest point of the heat pipe.
The working temperature of the heat pipe is determined by: the vapor pressure of working fluid and the pressure in the heat pipe.
A well designed heat pipe can achieve supersonic vapor flow, moving lots of heat.
A quick analog (on a large scale, is a single pipe) steam home heating system. bulb=boiler, pipe=pipe, cold end=radiator.
However, with a heat pipe, the temperatures can be designed for the application, but the fluid still travels downhill, and steam up.
Dave J.