1) It uses the project's URL slug if no package-as is specified. There's no reason to parse the source URL attempting to figure out which portion is the repository name when all that's required is a simple field in the pkgmeta file.
2) It isn't directly visible from GitHub, but anyone who decides to clone your repository will have that information either via their commit GUI or by typing "git log" from a commandline.
2: The changelog is all commits between tags. The e-mail address and all of the other information included there is the same information that is readily available via GitHub; in fact, that's where the information is pulled from.
We're pushing out an update tonight that handles lightweight tags; it was actually ready to go about an hour ago, but an unrelated issue pushed it out a bit. I'll post here with an update when it's live.