The MIL model has MIL adjustments and the Duplex model has MOA adjustments.
Any of the options listed will work. You just need to determine what color illumination you prefer and whether you prefer MOA or MIL to make your adjustments/reticle. The Duplex reticle is a simple set of crosshairs, while the MIL reticle will have stadia marks on the crosshairs to help with bullet drop estimation and hold overs. So that should help decide which you prefer, a plain set of crosshairs or a set of crosshairs with measurements on them.
The reticle will be visible regardless of the illumination or not. This is a standard riflescope with a standard reticle that can be seen without any illumination from the reticle.
The reticles will be approximately the same widths and the only major choice you need to make is how busy you want the reticle to be. If you want some hold overs the mil/moa crosshairs would be great options, but if you want it to be as simple as possible then the duplex is the better option.
The ocular lens diameter is not provided by Trijicon and most manufacturers do not provide the ocular lens diameter unfortunately. The outside diameter is provided at 1.7 inches, but the actual lens diameter is not. You will need to reach out to Trijicon directly to verify the exact diameter of the eyepiece diameter.
The only major differences between the AccuPoint and the AccuPower is that Power uses a battery for the illumination while the Point uses fiber optic/tritium to self illuminate so it does not require a battery. The Point is somewhat dependent on the amount of light available around you while the Power does not and just requires that the battery not be dead. Another major difference is that the Power is slightly more geared towards the tactical shooter because it has more involved and detailed reticle options over the Point which has slightly simpler reticle options. The Point also has different reticle colors because its illumination is tritium/fiber optic based.
There is no sunshade or kill flash provided by Trijicon for these scopes. There is no objective Butler Creek cover that is large enough for the objective, but the eyepiece can use MPN:MO20190.
The reticle is etched into the glass of the lens so even if there is no power in the scope, you can still use the reticle.
Mounting equipment is not included with this scope. While the exact needs will vary on the make, model, and caliber, your assumption is generally correct for an AR-15. 30mm rings with a height of 1.375" to 1.5."
Yes, it can.