Mo/W to Mo/Me?

I am tempted to change my Mo/W's secondary so that it will be a Mo/Me. However, when you change your secondary, can you go back and do the quests again to gain the Mesmer skills on this char? Or do I have to go buy them?

Also, could someone post a good Mo/W build? I know of the Healing Monk w/ Bonetti's for energy and "Watch Yourself!" for spammage. How about a tank or damage build?

You can do the quests to get mesmer skills or you can buy them, but you can't redo the ones that give you primary and secondary skills.