No, these sights are not designed for the S&W Shield line, including the 45 Shield; they only fit the M&P, M&P M2.0, SD9 VE, and SD40 VE models.
Yes, these Trijicon HD Night Sights are compatible with the M&P 40C.
The Trijicon HD Night Sights for S&W M&P only fit the M&P, M&P M2.0, SD9 VE, and SD40 VE models. (Excluding M&P SHIELD & C.O.R.E. Series). Trijicon does make a heavy duty night set that is compatible with the Shield Plus that you can find using the following link:
https://www.opticsplanet.com/trijicon-heavy-duty-night-sights-orange-front-outline-s-w-m-p-shield-sa139-c-600.html
Yes, the SD models will work for the SW9VE
Yes they will.
Front height: 0.215" Rear: 0.292"
Front: 0.215" Rear: 0.292"
The MP Shield version of these sights can be found in the links below:
https://www.opticsplanet.com/trijicon-heavy-duty-night-sights-yellow-front-outline-s-w-m-p-shield-sa139-c-600.html
https://www.opticsplanet.com/trijicon-heavy-duty-night-sights-orange-front-outline-s-w-m-p-shield-sa139-c-600.html
These sights will not work with the Shield EZ model.
Yes, you can use either just the front or rear of the Trijicon HD XR sights on your M&P 2.0 Compact, but please be aware that if you plan to use them with something that isn't a Trijicon rear sight you will need to verify your point of aim and point of impact with the new setup.