I run the exact driver and diode you are looking to get on two 16340 cells. With a single 18650 cell(Panasonic 3400mAh cell which is one of the best available) I only attain 162mW out of the full 303mW I get on two 16340s. This means that a single 18650 cell does not supply enough voltage and two 16340 cells must be used for full power with that exact setup. On the other hand you can intentionally run on one cell for the purpose of turning down your laser. You also have the option of using two 18350 cells which are a little larger than a 16340 but you can still use two of them and get a little more runtime than with 16340s. They are wider and a little longer than 16340s though so sometimes they can get a tad snug in some hosts but I can always use them in my C6 builds.
As for the focus adapter, Moh's adapters are nice so if the extra cost doesn't matter to you go with it. I don't bother with GITD on any of my red or green builds since they don't charge it but that's purely personal preference. I do however love GITD on 405nm and 445nm builds.