Best Practices – images & social profiles

I am working on a BuddyPress social site for the family and have two quick questions.

1) In the extended profile section I’ve added fields for people to put in their social profiles (Linkedin, FB, etc..) Is it a better practice to let users put in the full URL to their profile or just the name on the profile ie: http://www.facebook.com/sandy.fischler vs sandy.fischler and handle the URL at the code level)? I’m thinking it would be better for the older/Luddite users to just copy/paste the whole profile URL rather than confuse them with just the account name. Anyone have any experience here?

2) I’m using icon images for links to social profiles on my profile page and a code snippet in a bp-custom.php file set directly in the root Plugins folder because I like the idea of being able to change the theme and not have it mess up the icons. My icons are currently living in an images folder within the theme I’m using but if I’m going to be independent of theme, where should those image files live that isn’t in a theme folder?

Thanks & happy holidays everyone!