#1
the 17th fret on my e string doesnt play, it just rattles, after i looked closer i could see that when i press on 17 it also hits 18.

how can i raise the string the smallest bit?
#2
if you are happy with the action stone the frets.
its cheap 30 pounds an it will be better and wiser.
trust me.
been repairing/making guitars for about 3 years now.

#3
you need to raise your action. it depends on what type of bridge you have.. pm me the make and model of your guitar and i'll tell you how to do it.