The readme.txt included in the package!
However, I have planned to put it on the website soon too :)

I think you'll move the camera / pan more often than you box select, which is why I kept the most common action on the most accessible button. I may put in an option to reverse those two combinations

So, alpha blending:
Src * Src.a + (1-Src.a) * Dst
Premultiplied alpha blending:
1 * Src + (1-Src.a) * Dst

Right? ( Just making sure )

Alt + LMB drag, unless you found a bug not allowing you to do so :)

Well, nobody reads readme.txt files, so I don't blame you

There are hotkeys in the readme.txt included in the asset, but it would be a good idea to have it on the website as well!

This is already possible in the menu bar on the left :)
Blending & Depth -> Face Culling -> Double Sided
(Which is the same as Off)