2 Questions with Invite Plugin

2 quick questions:

1. Right now the plugin tag pulls the SITE_URL, however it reverts back to the main site address, not the sub-domain that the sub-site is running on.

2. I see that there is a plugin tag for USERNAME. Is there a way to pull a display name. It would make more sense to use the persons name versus user name since most people don't always make their user names recognizable.