You can use a variety of things for a host. C6 flashlight 501b flashlight, or go custom host from sinner, mrcrouse, ehgemus , but those will be a bit pricey . I also had one in a c11 side clicker I like a lot.
The driver depends on the host and how many batteries you want to run. With one battery you would need a boost driver, and two batteries an x drive, buck drive etc. current is up to you how hard you want to push the diode. 1a will give you anywhere around 1w and my c11 is running at 1.8 putting out 1.6w. The lens will also be a factor with power. A three element will give you a cleaner dot but sacrifice power . A g2/g9 will give you up to 25-30% more power but the divergence and dot will suffer. Lots of options here for what you want in the end.
Thanks guys, i went with the Cree XML t-6 for a host and using two 18650 4000mah batteries. I have a G2 lens.
On a separate build I want to use two disposable 123, that should be ok if the buck board is requiring 6V-7.2V? The host I'm looking at holds two 123s