To start off, I would like to say that I FRIKKEN LOVE the mining laser. It is the single most useful item ever created, though its use can be pretty complex at times. In this tutorial I will attempt to explain its workings, and hopefully you will learn something useful to your Minecraft experience. As MC or IC change, I will try to keep this updated as much as possible.
Part One: Usage
First off, lets go over some basics of how it works. Upon rightclicking, your laser will fire based on which mode it is in. Something to note, (most) laser bullets will travel forever until they hit blocks. For the purposes of this tutorial we will call the time in the air "flight-time" and time digging through the ground "ground-time". Once the laser bullet hits the ground, it will begin to burrow or perform whatever it does. As you probably know, you hold "M" and right click to change modes.
Another imporant usage tip is to always fire along at least one axis of a block. If you don't, it can get pretty messy as the laser won't properly cut a hole.
-Charging information to be here when I figure it out-
Part Two: Modes
Mining:
Flight-time: infinite
Ground-time: a reasonable value, around 16 blocks
Energy use: 100 shots on one charge, very good
Combat damage: it will take three hits to kill an average monster
Notes: This is your bread and butter mode, and you should use it most of the time. Good damage, high range, and great energy usage make it the most well rounded and possibly the best mode to use.
Low-Focus:
Flight-time: ~2 blocks
Ground-time: 1 block
Energy use: some absolutely obscene amount of charges
Combat damage: punching is seriously better
Notes: This mode is useless for pretty much everything except precision removal of blocks. In essence it is a super-pickaxe.
Long-Range:
Flight-time: infinite
Ground-time: very high, maybe 32 blocks
Energy use: 10 (9) shots
Combat damage: BOOM headshot!! (1)
Notes: The .50 cal of lasers, it will fly forever go through anything and annihilate all in its path. The energy usage is quite high, but its insane damage is definitely worth it.
Explosion:
Flight-time: infinite
Ground-time: dynamite explosion
Energy use: 10 (9) shots
Combat damage: 3 shots to kill
Notes: Honestly, this mode sucks. It has a massive energy usage, but the damage is low and the ground-time is the equivalent of a stick of dynamite.
Spread:
Flight-time: infinite
Ground-time: a reasonable value, around 16 blocks
Energy use: 4 shots
Combat damage: 3 hits
Notes: This mode seems epic, but it really isn't. Its only use is to blast a hole in a wall or rape something into nonexistence. Not viable for combat at all, or anything else really.
Hopefully now you have a good understanding of how the laser works, and can use it to its full potential!