Hi @Donna480
Firstly, your place looks amazing!
I am so sorry someone thinks its ok to take advantage of your generosity but also I think your expectations may not be as well defined hence why some may feel so compelled as to abuse it (still does not make it acceptable). From my experience, talking, specifying such things in my rules and printing/posting them around the house or common areas helps in really making these points get through to the guests, I also mention these upon or before booking.
Regarding the uninvited guests coming to use your equipment, either specify clearly this is not allowed and stick to it or accept it but maybe consider getting a simple "Accident waiver and release from liability" form which they must sign before giving them access to this area and your equipment. I doubt an accident will happen but its always better to protect yourself from any potential lawsuit.
@Fred13 your place seems quite similar, any input you could add to this?
Thanks,
Yadira