The "it should be closed for another reason…" flag is the flag that should be used to close a question that is not duplicating another question. In fact, the previous flag is "it is a duplicate…."
It is different from the "other (needs ♦ moderator attention)" flag, since the first adds the question to the Close Votes review queue, accessible to all the users ...
It's now possible to retract a raised flag. Once flagged a post, clicking on flag will show a dialog box similar to the following one.
Instead of the Flag Answer or Flag Question button, there is the Retract Flag button that allows to retract the raised flag, and eventually flag the post for another reason.
I second this. Yesterday, I posted comments asking somebody with a (IMHO) very confused question to improve specific points. This morning, the user had added some comments that did not improve things (they made the question even more confusing - again IMHO). So I flagged it as "low quality".
Then, I few hours later, the OP had cleaned up the question. ...
The limit is a system wide thing; all of the SE sites have the same behaviors, apart from a few minor differences.
There is a limit because the spam/offensive flag gets misapplied and abused on some of the other sites. As your flag weight increases, you get the opportunity to flag more things per day.
The first answer was automagically processed by the system, which marked the flags as helpful.
The second answer was handled by me. I dismissed the Rude/Abusive flags as not helpful, as this post was rather neither rude nor abusive (and not spam for anyone wondering). I marked the auto Very Low Quality and Not An Answer flags has helpful; both were ...
The declination doesn't have any meaning when applied to a question; it is specific for answers that are flagged as not answers. I would have chosen the one saying that a moderator reviewed the post and didn't find anything wrong.
I guess the moderator got confused from the flag talking of an answer. It happens to us too. ;-)