Hey meee,
Do your housemates know what you do?
If they don't then its a question of ethics, I personally wouldn't be able to let clients back to the house. At the end of the day it is there safety too, and it's not fair to put it at risk without their knowledge.
The fee you decide to charge is your decision, so is whether you decide to charge the same as an outcall or more.
Each girl takes different security measures, but personally I use a safety buddy and make sure I screen clients properly. I also give clients a landmark to get to, and then when they get there, they phone me and I give them the address.
Have you considered working from a hotel one day a week? You could do a trial day at a cheapish hotel, and advertise on your website or profile that you will be doing incalls on that day only, and see how it goes. If it goes well you could do it once a week or something.
xx