Its all about exposure. He can take what has been said here and use it in games in the future. We have only told him what might happen if he might attempt certain things. As for the gear you are looking for indeed check out your local arena and shop for prices and details. Thats a good want list for what you want to start out with. I would suggest getting the sniper last because (Not knowing what indoor facilities you have out there in PEI) some indoor fields are either to small or have FPS limits that most if not all snipers go over. I would focus solely on getting your SMG skills up to snuff as well can getting your kit up there with your mag pouchs and radios(If you join a team). Then worry about expanding. Get good with the basics then advance.
You say that you have only done Skirmishes with your friends. Its a bit different when running scenarios or attending milsims. You hav eto get good with what you know then expand into other roles. You sound more like a recon/scout with how you said you like to play. So gear for you might be a battle belt with a few pouchs and a dump pouch, so you can stay fluid and move more efficiently. This can be brought up at your local store and the owners can direct you to the shinies from there.
If you need any help just PM me.