question plz help

if i am in a luxon guild and go to the luxon cities and do the luxon missions will i be able to go back and do the same on the kurzick side? and also can i buy armor from either side after iv done stuff on the other? thnx in advance

you will be able to access every single place. the only thing you need to do is to befriend the kurzicks, else you wont come farer than the 3 outposts after HZH. when you befriended them, you simple follow the primary quests you get, and end up having both, luxon and kurzick land explored.