kinks in the string can be a major problem for fret buzz etc.. and a lot of people could benefit from changing there strings once a week.. but it's expensive lol.. i change mine as often as possible.
oh and the beat it solo isn't impossible just keep hacking at it dude.. the hard parts are the 9 tuplet tapping and the little nuances in the playing that only EVH really can do.. but getting the feel/essence of the solo is do-able.