Hi Matthew,
I may be reading between the lines here, but it seems as if you are getting the clearest communication in short, tapped out phrases, seemingly from the wall. Am I right? And then, in addition to that, there are strange occurances of reappearing objects, moving, thumping tables and chairs, heat or touch on your arms or legs, visual tricks, and stuff like that?
Ok. So, based on the above, and the fact that you do not seem bothered by the touching (which would be way out-of-bounds for me) this is what I suggest. Find a way to communicate more clearly with the one you are thinking is your spirit. Try a ouija board, spirit board, or automatic writing. Once you work out a groove, you will see, it is just like talking to anyone else.
I also strongly suggest . . . And this is important . . . Work out a signal or code so that you know who it is you are "talking" to. This strongest spirit, the one you have come to know and recognize the best can act as a sort of "gatekeeper" for you. If you do not get the signal, especially while this all still feels new to you, shut off communications. Stop. In time, you will be able to tell, just from the feel of the spirit, their little quirks and habits, who is there. Just like people, because indeed they are people, you will be able to tell when it is serious, or playing around. You will know who and when to trust, and when they are, as you said, sinister. Hope this helps.