Fulton everyone you can at first. Fill your staff so you can develop good shit. When your staff units fill up, you will automatically put the best ones into the units that they fit in. Upgrade your binos you can analyze what skills they have, and wether or not they're worth rescuing. But at that point in the game you're better off just fulton-ing everyone you see.
And on that mission you only need to take out 1 tank to complete it, then just fuck around for the rest of the time, or complete the optional objectives. Remember there are no checkpoints in the mission so if you die, you're back at the start.