This sounds like a lot of fun, I have Arma III but no mods -yet. I'll have to join you guys next weekend if there is an OP happening. It wasn't quite clear from the above text, are those mods required for me to be compatible with you guys or are they just suggested?
You are welcome to join. Most of the mods are required to run the mission, other than the one flagged as (optionals). I recommend
http://play.withsix.com/ to manage mods. The mod list are the names exactly as they appear in playwithsix.
You will also need to setup Task Force Radio, which is the comms system. If you look in the posts for the mission, 1st Mar, I gave links to TFAR and AGM. The latest version of teamspeak works with TFAR, you can get this by Googling. It doesn't matter if it's 32 or 64bit.
For TFAR there are a lot of good guides on how to install on YouTube, again search for ARMA 3 and TFAR or task force radio and they will come up. They show you step by step where to go and what to do to setup.
AGM is a mod which simulates a greater real world interaction and medical situation. One can use self interact on any mission if you are running the mod to practice, but you can only interact with other players on MP.
For key binds, TFAR needs your team speak key to be proximity chat, most use tab, and caps is your infantry radio. Forget long range comms for the moment. Tab clashes with Agm's weapons rest so you will need to change this, most use ctrl space from a previous mod's key binding.
You can change all AGM key bindings by launching the mod, running a mission, any SP is fine, and then esc key. Top left you will see agm options bar, click and change to your hearts content. I recommend keeping as much default as possible because if you then ask a question of another player they can help. If you've changed it they can't help.