Little help with runes here

OK, so i have this mesmer rune and im a EM/ME. Does this mean that this rune is only for my 1st profession or can you have Primary/Secondary Runes for your character.

I also have some purple items, and the adv kit but i havent made my own rune yet.

Mabe since i have a mesmer rune...thats why i cant apply it to my armor ?
If so that would answer my 1st question.

How many runes can one character use ?

P.S.......IM me if you have anything for elem....runes, fire wands +10

unless they changed it, you can only use your primary profession's runes.

Do you have to customize a salvagable item to extract the rune ?

Or do you just expert kit-it ?

Just use the expert kit.