Yes, #P1e General Discussion is probably the best place. I wanted to simplify the number of communities we had, so I consolidated some of the PF1e into General. If demand for 1e subjects comes up I'm totally happy to create specific communities for it.
The URL field is for if there is a link you want attached to your post. I.e I want to post to start a discussion about a Paizo announcement on their website, I can put the URL to the announcement in that field and then my comments to start the discussion about it, and users will have a direct link to the referenced Paizo post. It's optional, though, you can create what is considered a text only post that is just for discussion of you want.