Modding affects the console.
no it only affects the modded account.
Modding your 360 does not affect anything in a negative manner. Your original discs will work the same as they did before. -Personal experience from modding XBOX 360 for 3 years.
By deactivating it, I mean as their primary system. I bought a PS4 that I thought was brand new but it ended up having someone else's account on it, didn't have access to internet to deactivate my console as their primary system. Will it cause me problems with my console?
It can do alot. Some make your comp. slower. And some can wipe out your entire hardrive. It depends on the virus.
nope
It affects the saved data on your hard drive to see this you can see other profiles on your hard drive. And if your wondering you can't cause permeant damage to your hard drive you just may loose progress you had on that game
Yes Console region doesn't affect controllers
yes
Yes, you can. Simply remove the hard drive then insert your new one. Unless your Xbox LIVE account is on the old hard drive, then it will not affect your Xbox LIVE experience. If your account is on the old hard drive, you can move it by selecting it inside of your Storage settings, then hitting Move. After that, just choose your new hard drive and the transfer will begin.
No, having a YouTube account will not affect your computer in any negative way.
No, it will only affect ur joint account. Then cannot touch your other account.
Yes, magnets affect any electronic that stores information. So your console can become corrupted.