How do I get different secondary profession skills?

I switched my secondary from mesmer to monk recently. I'm wondering if I can get all the monk skills from quests i done while I had mesmer as secondary? I have been reading that you can talk to the npc, and I tried, but none of them offered me any monk skills even though i finished those quests as a mesmer secondary. I sersiouly hope i don't have to buy those skills...

You can't do those skill quests again. However, there are other, monk only, skills quests that are you can now get. There's a list of all the skills quests on guildwiki. http://gw.gamewikis.org/index.php/Skill_Quests

So if i don't accept the skill rewards until I complete change of secondary profession and then go back and accept all the rewards, would the skills given would mirror my new secondary profession?

yes the reward is on youre current primary/secondary