The other day, a friend of mine suggested that we go visit a Russian Orthodox church.  Neither of us is Russian Orthodox, but my friend particularly likes visiting beautiful churches, and he's visited that one before.  We ended up not going, but may in the future--and I have a few questions.

First, my friend said that women have to wear headscarves in Russian Orthodox churches.  When I said I didn't have any such thing (I don't, and honestly wouldn't even know how to put one on), he said they provide them.  Is that true?  If you have a scarf of your own, does putting any scarf on your head any way meet the requirements, or is it more specific than that?

Second, when he made the suggestion, both of us happened to be wearing jeans.  I wanted to know if that would be acceptable.  Or are women supposed to wear skirts?  Should men wear "better" pants, or are jeans acceptable?  He didn't know; I hope someone here can tell me.

And are there other things a visitor to a Russian Orthodox church should know?