Clipping the standard Peco 'motors' to the point is all that is needed. This is how they were designed to be used. Problem was that it was more difficult to ballast the bit of track where the point motor is as there's a big hole under the track. They can also be mounted under the board and have a small hole drilled in the board for the actuating pin to work through. Although Peco now have an adapter plate for this purpose, they only made it available after similar plates were made in Australia and USA. The Peco adapter is just their above the board adapter without the sliding part.
I haven't tried the low current versions yet. They aren't necessarily for DCC. Just low current applications - such as the cheap power packs sold in many sets. Not really sure why they persist in making the two kinds.
As for the different Peco ranges. The Peco Setrack is made to the standard British geometry and is just the UK version of the snap track by Atlas.
The Code 100 and 75 streamline systems are pretty much identical apart from the rail height and some components such as the 3-way point (one is symmetrical, the other asymmetrical respectively). I think the sleeper spacing is the same too. The small, medium and large radius all have the same diverging angle. This means you can have a crossover between parallel tracks using a large and small radius point.
The code 83 track is aimed at the US modeller (wherever they may be residing). It conforms to the usual US practice of numbering turnouts according to the angle of divergence and has a more typical sleeper (or tie) spacing and dimension, including the square cross section. For US modellers it's clearly more representative of local railroad track than the standard Peco range. Some broad gauge modellers here find it looks more like broad gauge track too.
Then there's the various Peco narrow gauge ranges. But I won't go there.