Yes, the Troy Folding Front Battle Sight can co-witness with the EOTech OPMOD EXPS2.
The TORY M4 Battle sight will work with a M16 Carrying handle. I personally have done it myself.
The Troy Iron Sight is a standard height AR sight so it should work fine with the Matech Rear Sight.
The Troy Industries HIVIZ front sight post will fit the Troy Folding Front Battle Sight HK Style Sight.
This will work with any standard height rear AR sights.
The HK sight is 1.5oz and the M4 is 1.45oz.
One will not have an advantage over the other in low light.
These are standard height sights.
These are standard height sights and will co-witness with your red dot if your red dot is using a co-witness mount.
A tool is not required as all that needs to be done is the front sight post plunger just needs to be depressed and then the post can be turned freely. But a front sight tool will make things much easier. You can find many options under "AR front sight tool" or "A2 front sight tool" and here is one of our most popular options:
https://www.opticsplanet.com/leapers-new-gen-utg-ar-15-front-sight-combo-tool-scp-a1245-a.html