You do not need a mounting plate to mount the Trijicon RMR Type 2 to the Trijicon RMR/SRO 45 Degree Offset Mount w/ Trijicon Q-LOC Technology.
Yes, the Holosun 507C uses the Trijicon RMR optic footprint and would be compatible with this Trijicon RMR/SRO 45 Degree Offset Mount.
The Trijicon RMR 45 Degree Offset Quick Release Mount will fit Holosun red dots with the RMR footprint. So the Holosun 407C and 507C will fit this mount.
The Trijicon RMR 45 Degree Offset Quick Release Mount features the ability to attach to either the right or left side of the weapon. It also has return to Zero features in a low weight, low profile design which works with any Picatinny rail.
No, the RMRcc does not use the same mount as the RMR. It is similar, except it does not have any lugs. I have not seen anyone that makes a picatinny adapter for it.
Yes it will be compatible.
The height is not provided by Trijicon, but my educated guess for actual height over bore when mounted to the top rail of an AR-15 handguard specifically would be around 2 inches.
You should be able to install it in conjunction with an ACOG RCO, but please be aware that you can also mount to the eyepiece of the actual ACOG and you can always mount in front or behind the ACOG instead of trying to squeeze it under the scope as it provides no real benefit.
Yes, the Trijicon SRO and RMR share the exact same mounting pattern so you can also use this mount for an SRO.
No, Trijicon only offers it in a right handed option. There are other options, but not from Trijicon. Please email us at techsales@opticsplanet.com and we can look into options for you.