Installing an Apex kit in an M&P is not rocket science. Occasionally you find it takes a bit of manual dexterity (and patience) to get the little parts lined up so that pins will go back in, but no gunsmithing skills are involved.
I have done lots of these, and changing the striker block is no big deal. In the beginning I removed/installed rear sight with a punch and hammer; now I use a sight pusher -- either way works. As for the rear sight Allen wrenches, from memory it is a .050", but whatever it takes exists an any SAE Allen wrenches set.
Two hints:
S&W usually uses a bit of red Locktite on the Allen set screw, so it won't want to start turning. You can muscle it and maybe either bend your Allen wrench or, worse, strip the hex recess in the screw. If the screw doesn't turn with normal force, stop and apply heat. You don't want to put a torch to your pistol's slide; what I do is heat up a soldering gun and put the tip directly into the Allen screw. Only takes a few seconds.
For those who have done M&P 1.0s and are now doing a 2.0, the order of steps is a bit different, primarily involving the takedown pin/lever. Read the directions or watch one of the videos.
Edit: Another hint:
If you're only going to do one of these, you can use a .45 armorer's block like the guy in the video, or even that old standby, a piece of 2x4 with some holes in it. But if you're going to do more than a couple, get the red Apex M&P Armorer's Block. This keeps the frame from moving around, and all the pin pass holes are already lined up.