First check all your gaskets because the chrome should not connect to the interior (if you look closely at my sig I dont have most of my chrome). However it is possible there is some leak due to whatever reason. The chrome normally just pops off and the only thing you should worry about is the plastic mounting nuts. As far as sealant I can't really say... I'd assume something similar to what you use on gaskets if nothing else check out your local auto store (I like using advance auto for generic stuff). If I get a chance I'll look something up for ya.