bimaman said:
Is there a way to upload from a twitter post that has multiple immages...
Yes, use the batch bookmarklet.
...while selecting which picture will actually be featured when using the original post's url,...
Not sure what you mean here. If you're talking about being able to set which image is parent, then yes, that is possible.
...or do you have to use each immage's url independently (and lose automatic access to the metadata of the post)?
Images from Twitter should always be using the Tweet URL as the source, even if multiple images will have the same source because of that. See Howto:Twitter for more information.