I use the lockblock style mounts and they work well for me. I found some generic copies on ebay, and they are fine.

That looks like a nice light and if it's really 820 lumens you will be amazed at how much light it will throw out. You'll also need some 18650 batteries and a charger. You can find recommendations here for those.

The nice thing about going with the drop-in lights is that when the inevitable next generation lights come out, you can easily upgrade without starting over. Good luck and ride safely.