Well, I always try to have 1 Power Weapon and 1 Kiss, so I can do well against all opponents. For my squad sizes, I try to have 6 man squads to go in Venoms, and one larger footslogging squad to go with a Shadowseer.
Mimes should be used in large groups, assuming ou can infiltrate in the mission being played, and should be armed the same way as the Troupes, in my opinion.