There is a carcass for a few seconds after she dies just like every other mob in the game. She doesn't "Obi-Wan Kenobi." Your second point is as I stated, a frustrating aspect. There is shared credit. When I got the badge earlier today, I was on a team of three and the team leader bopped her ( not me) and we all got the cred. I don't remember the exact wording for the event that occurs in Croatoa, but there is a flash (if you have the event dialog enabled in chat) that says something like, "There is unusual monster activity spotted in Croatoa." The stand-alone, no, I don't think there is a flash.
As for your second edit, until today, I didn't know and still don't know if the 45-minute timer is official. It could be and for this small sample, seems to be the case. I was under the impression that it was a 30-minute timer and when Sally didn't spawn, I assumed someone had beat me to her and therefore could not possibly know when to hunt next. I'd rather not have to spend a couple of hours or even an hour hopping or flying around the lake hoping to get to her first when I could be running missions.