No it's not bad. Go have fun. Maybe that will light a fire under the crush.
Hypothetically, if you know someone has a crush on you, but someone else asks you out, is it rude/bad/mean to accept?
Nope, but maybe if you plan on going out with your crush right after that date 😂 You don't owe them anything, you do what you want.
Not at all. Consider it a test of feelings,
yours and there's. Some times,
only time can tell.
Of course not. Actually I would like to recommend this person to try dating resources like for example this one here because it will help him or her to forget about you. Probably this person will be able to find someone who will truly love him so I recommend you to talk about it there. Good luck.