why dont you just lock your device with password?. Is it because he plays games and you allow him?. Then do one thing there are certain paid apps which you can buy from app store which can lock down particular apps.
So you are telling that you put your mac to sleep and then your mouse is not working and it wants to connect to a blue tooth mouse?. How does it even make sense?. You have to check your mouse in other mac as well and see if the mouse is okay or not. Did you get any cd for your mouse?. If you did then install it.
I think you have a virus, yes you have to delete the chrome browser and re install it. But there are chances that even by doing that your problem might not get fixed. Do it first and see if it solves or not. If the virus has got into your system then whatever browser you choose you will be facing the same problem.
If you are afraid that your desktop is full and that is why it is not working, then as you are not finding the files you have recently transferred, so you should delete some other files and free up some space to see if it works or not.
What did you meant by usb port?. Did you plug in your device without a adapter to charge your phone. Every adapter has a usb port to connect your lighting wire. I did not understand what you meant. There are some multi plugs where there are usb ports, did you connect your I phone in any of that to charge your phone?.
Yes, sometimes I tunes makes us face these problems. Did you log out and gain login into your I tunes once you have failed to connect?. Sometimes I tunes get hanged up and does not work and all we have to do is just reenter into out account.
Does it also happen when you connect any bluetooth headphone with your mac?. Please check it because if it does then there is nothing to be worried about, it is just a software problem.