Hmm; very interesting. Now, I'm actually one who hasn't made up my mind on most things in that spiritual sense.
I guess, I should state what I do believe in that sense first.
I do think that a large number of ghosts and other spiritual things have some physical cause, or are otherwise not 'mystical'
I'm kinda skeptical to say all incidents are like that though...
My mom's a highly spiritual person in all senses of that word, and she says she often senses angels and things like that, and I certainly believe here, and my father's occasionally sensed stuff too.
It's true that exercising your spirit puts you more in touch with spiritual things!
I myself have only really seen something once. Friend were playing with a crappy Ouja board, Me and another said we didn't want to play and sat in a corner and I was playing pokemon.
And then all of a sudden there was this big floating thing with a hand coming out of it O_O
Freaked me the eff out. A couple of other people saw the hand, though they didn't see what it was coming out of like I did.
Still don't quite know what that was. I thought it was a ghost, but on consideration, I'm not sure. Other than that I sense people who aren't there all the effing time. Usually when I look, and see no one the sense leaves, but often enough it lingers and bothers me and my lack of sanity XD
Of course, I don't know what to think of those personal experiences, as my own sense of reality tends to be thinner than most, not helped by the fact that I will believe most everything if I see enough proof. I almost feel if I tried enough I could bend reality...
but would I be bending it for everyone or just myself? And that, my friends, is the difference between sanity and insanity.

Anyways. That part being said, i do highly believe in spiritual gifts. The spirit is an organ, used to contact God and all sorts of things that don't make sense, and God has different spiritual gifts for each person. My boyfriend can sense people's aura's, which is neat, but bad when he meets icky people cause then he gets a really gross feeling and I feel sorry for him cause he feels sick DX

I'm getting off subject here XD
I guess, what I should say is, I don't doubt that what you are saying is true;
Now, the main issue is, it seems some of these things are causing you a lot of anxiety. The first issue would be to find out if anything is physically based; perhaps a air conditioner at a weird frequency, etc etc etc, although as it seems the events aren't very based on places. Second would be to see if you are the only one experiencing these things, and at least with the case of your dream you and your friend shared, that would not be the case.

So, then you'd have to battle spiritual with spiritual, as I see you have your own methods of doing. I don't really have an opinion on those, I don't understand the tying in of crystals with spirits and all, not to say it's not real.
I do however firmly believe that the mind/spirit has much more power over things than many people believe, and by exercising your own spirit, you can control these things, even without other items, and that even at least partially some of the power these items have is power you are giving them by placing your 'faith' in them.
I think, if you start empowering yourself, you will be able to send them away, perhaps even like your mage-friend did.
Speak out loud when they come next time, tell them that you won't tolerate any bad behavior or ill-intentions in your house. Speaking helps exercise the spirit!
It probably will be hard, and I apologize as I am not as strong of spirit even myself, though I'm working on it, and neither do I fully understand your situation, but the spirit properly used will have power over just about anything.