Kill The Guards
When you do reach the rendezvous point, you'll make an unpleasant discovery: all of Tarfful's resistance fighters have been slain, presumably by the Trando slavers in the area. Let Tarfful kill them off while you send soldiers into the sniping and anti-armor spots here. It's important that you don't head up the ramp yet, though; a Grievous bodyguard will appear, so use the lower two positions to take it out. No need to worry about taking damage here, as there are plenty of bacta dispensers in the area, so kill it, then heal everyone in your squad before placing them back into the two positions.
When you're ready for the second bodyguard, send one of your troopers up to the anti-armor position above the ramp; doing so will cause the second baddie to spawn in. (You can also try to send the squaddie to the sniper position above the ramp, but they seem to run into a pathing error and will usually get stuck on the ramp, making them easy prey for the guard. With three soldiers in different positions, you should be able to dish out enough damage to quickly take down the guard, after which you'll be able to move to the next level.
Search and Destroy
Locate Separatist Cruiser
Your Wookiee guide unfortunately won't last too long, so you'll have to proceed on your own. After a couple of hallways full of droids, you'll come to a nasty surprise: an interior spider droid. There aren't any special positions for your soldiers here, so you'll have to make some by shooting the gas tanks around the droid. When you do so, get them into an anti-armor, grenadier, and sniper position, then do your best to help whittle down the beast's health from the sidelines.
Quickly destroying the dispensers will let your Wookiee friends...do something or other. Regardless of their purpose, you have to keep one alive.
After the spider droid, you'll have to deal with a number of SBD's in the next hallway, so bring along some anti-armor charges or EC grenades before moving on. In the next long hallway, you'll find an anti-armor and snipe position, so place your soldiers there before moving on to trigger the droideka spawn. When they're down, return to the bacta dispensers, then move further up the hall to take on another spider droid. No secret here; just get your guys into position and repeatedly reposition the anti-armor soldier so that he fires rapidly. One or two of your soldiers will likely get incapacitated, so be quick to bring them back to the land of the living when that occurs.
You'll want to try and hang on to your EC grenades and anti-armor shells during the fight with the spider droid, though, as you'll have to bang through another four SBD's in the hallway beyond. You will have the opportunity to refresh your health after this fight, though, so heal up before moving into the Wookiee room.
Your goal here is to destroy two droid dispensers before they manage to kill your Wookiee friends. It's possible to get them both before either of the Wookiees goes down, but extremely unlikely; one of them is fairly exposed. The second one is in hiding, though, and will survive for a good amount of time.
To begin with, the SBD dispenser is going to be your first priority. Move into the room, using your AA launcher to destroy any hostiles, then set your team up in the AA position and the snipe position, with the third soldier setting a charge on the dispenser. You'll need to be mindful of the soldier in the snipe position, though, as a droideka will eventually roll up behind him and start shooting him in the back; these guys have no sense of honor! If you can handle that threat, though, your teammates should be able to keep the rest of the droids at bay while the charge is being set, especially if you continually retask the anti-armor soldier.
With the SBD dispenser out of the way, it's time to move your troops over to the droideka dispenser. The sniper can remain in position, but the anti-armor soldier likely won't have line of sight to any of the droidekas, so you may wish to just have him form up on you and attempt to take down droidekas with anti-armor or blaster fire. (There's another box of anti-armor rounds to the left of the door through which you came in, near the second Wookiee.)
When both dispensers are dead, you'll have to blow one of the empty fuel tanks here to move on. Don't forget to heal up before you exit to the next level.