Can using to much product when straightening damage hair? I also need flat iron help?

i straighten my hair. (every day. and no, i cant not straighten it) can too much product damage it? also, i went to the salon the other day and she straightened my hair and it was amazing how straight it was! (i have guy length hair) usually the ends of my hair are never perfectly straight. they are frizzy and im not sure how to control it. so should i get the chi flat iron she was using? i did notice it was on the highest heat setting...so will that make my hair worse in the long run?