I'm glad you're enjoying the game! And yes, the Explore option will have more content added over time and I'm constantly trying to make the leads and hints more helpful, so fingers crossed that solves any issues you're having in time.
Currently you can only invite four girls to stay in the manor - the house ladies from Jessica's storyline. Once you've done that event, and the girl's followup event, you can talk to Jessica in the kitchen and get her to invite them to stay in the manor.