Well, now I've read the thread, I am surprised by the number of firm 'no's'.
My son is six months shy of 14. I have never met any of his school friends, or their parents, except for one boy and his family.I have repeatedly asked ds to invite friends round in the holidays or arrange to see a group of them for a cinema trip etc but he tells me this is not what people do.
So if ds had an invite to a birthday party sleepover, it would inevitably be with a family I didn't know. I'n no fan of sleepovers, but for ds to have any sort of out of school social life with his friends, I would have to trust him at some point and let him to to things like this.
But I'd do the checking up thing first. Definitely phone the parents, introduce myself and hope to have quite a long chat with them. Would be worried if they seemed vague, uninclined to talk or very casual about the arrangements.
In your shoes, slowreader, I'd want to know how many adults are taking the group to the firework display, and whether there will be any alcohol at the party. Also have the parents held similar parties before and if so how did they go? I'd also want to know a lot about the sleeping arrangements, how many guests are staying over, if they are all from the school, their ages etc etc.
I might also phone up a parent of another guest, especially one who has been to the house before. Perhaps on the pretext of sharing lifts back, but also to get some background info.
We do have some friends who hold big parties for their children - they are nice people and good parents but they have a surprisingly casual attitude to 10 year olds swigging lager, so I know how house rules can vary.
Another thing to do - if your dd goes, can you accidently on purpose forget to pack something necessary? Let her go to the party, then phone the host in a few hours to say you are dropping of 'x' because you forgot to give it to your dd.
Say to them you are on you way already as you are in the area, turn up on the doorstep, suss out the situation and if you don't like the way things are looking, take your dd back home.