) Not very important, but I'm not sure how many people want to put personal details on couchsurfing.org. I'm also not sure about how couchsurfing.org works, but I would prefer for only people in the LW community to be able to contact me re: staying over.

You can create a minimalist profile on CS, no personal data, no pictures. You can say in your profile that you only want people from LW to contact you, it's as simple as that and there is nothing in CS forbidding it, people have arbitrary rules in their profiles. Add a requirement that they have to be members of LW for at least a few months if you want to be on the safe side.