Elzettas seem like a decent bang for the buck.  Looking at the Alpha specifically.  

1) Standard or flood lens?  This would be primarily for HD, but being able to use it outside of the home to a reasonable extent (<50m) would be nice too.  Does anyone have experience with both?  @Mrgunsngear did the video below, but not sure what it looks like outdoors.

2) What rechargeable batteries work well for them?

3) How does the ZRX picatinny mount compare to the VTAC mount?  I really like the latter and would like to reuse it, but since the ZRX is designed to go with Elzetta lights, I could be pursued to give it a try.

4) What's the best place to buy them?

1) Standard. Flood is great for across the room at most with only 235 candela, it will horrible for general use, and this is exacerbated by the already low (by today's standards) 415 lumen output of the alpha to begin with so there's no brute force to try and make up for pure flood.

2) No idea, shoot them an email or call tomorrow. I would love to guess 16350 that matches cr123a output, but cannot find anything on their website from a cursory search.

3) It's just a 1" ring mount the same as any other.

4) Direct to configure your own or amazon (which they sell through) for a preconfigured option.

To give some perspective, my 1200 lumen 12k-ish candela m600df with cr123 batteries is only good out to about 55 meters maximum to me.

The flood lense in an Elzetta would definitely be a no go for me outside of home defense.  That thing pukes light.  

Unless they’ve changed their lineup, the only Elzetta to take 18650s is the Bones.  

There just might be one for sale on the EE as well....

You are correct