cometic gaskets

just a couple of things i'm not clear on.
can you reuse cometic gaskets, and is copper spray ok for aluminum heads.
the reason i ask is i've made the change to hydraulic roller cam and didn't remember to clearance the pushrod bores. they are eddy rpm's. also i had coated the gaskets with copper spray. someone suggested that you don't use copper coat with ali heads.the copper coat i used was a vht product.
i have removed the heads for clearancing for pushrods and the copper coat cleaned off easily.
this is a new build.
thanks in advance for ya help.