To continue the story you'd have to talk with tavi you can find her near the mines think you first meet her in the showers i think it's been a bit since I did a new game she is the one who has a plan to escape the prison you just have submit to her (feel free to correct me)
To make more credits probably would be prostitution and upgrade your sex skills a bit
Portal panties isn't long just got to wait until one of the random events is you getting fucked at random and go back to alex for more info
There are 2 routes in the game (from what i remember) "bad" or "good" either basically mean nothing in the end I think at least until the story expands (again feel free to correct me) not saying much else to keep spoilers
Keep an eye on the "tasks" button it shows all quests that are still open and what to do next on the story.