Make a save file to be safe then sign the contract so you can play through the events at the mansion. Last time I played, after a several days in the mansion it reset where he asked me to sign a slave contract again. The second time I didn't and then just went on playing the game with no problems on the main quest.
I believe you have to play the mansion for one of the main quests (either Igor, the Master or someone else did/will assign it to you as part of their quest line). Also, going from memory, there are two ways you can end up at the mansion - one when you are whoring and the other when assigned from a quest, where you meet the limo in the area where the grocery store is. I think if you go while whoring it does not count for the story quest (I may be wrong), so wait and get it from the main quest.
Going from memory, I think the Master tells you to get extra training from Igor. Once that happens, call Igor and he will tell you to come by his shop on Friday
To work at the cafe with the special form (and later nude), I think it depends on your exhibitionist skill. If you have walked the town nude on Lena's quest the I believe you have maxed out exhibitionist skill, so you should be able to work at the cafe with either the special uniform or nude. Have you talked to the cafe owner about the new job(s) and accepted them yet? Because once you do you should be able to work in the uniform.