fish and milk

Question

a)Is it allowed to cook fish and milk together? b)fish and butter? c) fish and cheese? d)to eat cold fish and cheese that was not cooked together (ie lox and cheese) e)according to those that posek it is asur to have fish and milk, is that only cooking or also apply to lox and cheese. Meaning when bet yosef says that it is asur (whether it is a misprint or not) was he referring to cooking only or also eating together cold? thanks