Cantina: When you walk in, you'll encounter Calo Nord for the first time, taking down three Black Vulkars that just wanted to talk. Tip: don't let him count to three if he talks to you. You can collect on your bounties here by talking to Zax the Hutt, if you actually killed Dia or Largo. If not, you can attempt to persuade Holgan to drop his bounty, or simply buy his forgiveness with 200 credits. If you treat him right, he'll also tell you about his work as a smuggler for Davik, and his ship, the Ebon Hawk. Sounds like a nice ship.... Zax will also have more info on the serum for Zelka. You can also try to help one Twi'lek dancer get a job at the cantina if you can persuade her that you'd be a good dance partner. The correct moves are: dance close; dance behind; and dance close and face-to-face. Success here appears to be predicated on your dexterity, so if your character's not very graceful, you may wind up falling on your face instead of dancing.
Upper City Elevator Apartments: There's plenty of Black Vulkars just waiting to be put out of their misery here. You can take them on yourself, or repair a sentry droid to do the dirty work for you. There's also a bit of a puzzle here involving a security chest that's triggered to explode unless it's opened via holograms. You can check the desk for the combination, or just select the holos in this order: Elinda, Ujaa, Ujii, Loopa, Fodo, Ashana. The prize? A suit of Echani Fiber Armor, a light armor suit that's upgradeable and has a bit more protection than a generic Combat Suit. You'll also find Matrik, who has a bounty on his head from Davik
Northwestern Apartments: After another little run-in with Calo Nord, explore the area to find an even worse infestation of Black Vulkars than in the other set of apartments. There are some mines here; if you've maxed out your demolitions skill, you should be able to defuse them without incident. If you have no demolitions expertise, you may want to wait until Mission joins your party before wandering around in here. There's another puzzle chest, as well, that requires you to read a letter and answer a few questions before you can gain access to it. (The answers are: Hyperdrive, uncle, and Alderaan.)
Selvan can also be found in one of the locked rooms in the northwestern apartments. While bounty hunting doesn't quite fall under the purview of Light side activities, you can goad her into attacking you by simply walking into her room after she tells you to leave. She puts up quite a fight; you might want to activate an Energy Shield before waltzing in, guns blazing. She gives you a hefty 650 experience reward and has some useful items on her, so it's worth the risk. If you absolutely cannot defeat her with just Carth, come back after you add Mission or Zaalbar to your party and bust her chops.
Once you're done exploring, fight your way to the elevator in the northwest corner of the Lower City to enter the next area.