One of the things that can help, especially in a new job dealing with a new supplier is to call and discuss, briefly how it would work. A friendly call rather than an exchange of e-mails sometimes works better.
Maybe both those firms are just crap or maybe there are things that could have worked to make the experience easier.
I would certainly chat to the manager of the venue now, explain that you seem to have got off on the wrong foot and that you just want to make sure it works for everyone. Sort out the details now.
If you view her as some sort of menial she is unlikely to want to help you. She may not have the resources to do all you ask. It might make it unprofitable/more trouble than it is worth. I don't know.
I run a small business. Sometimes people treat me as if I am a multi-national. They want timetables and "options", they want to cancel and rearrange. They want meetings to discuss £100 worth of work, (meetings in their offices 20 miles away!!). I earn £XXX, the profit margin is tiny, I don't have the resources. I am also a trusted supplier. Treat me with respect as an equal and I will do a great job. Treat me like a disposable servant, "I am paying therefore you must do X" and I would rather not have your business.
I am not saying that is how you are OP. I am just saying that when dealing with suppliers a co-operative attitude sometimes achieves more.
The boss has chosen that restaurant for a reason. Maybe they have helped him out of a tight spot in the past, pulled out all the stops for him when it mattered, the owner is married to his sister...?? Who knows.
I hope it goes well OP. Good luck