Except/ except for/ with the exception of

Please take a look at the following 3 sentences.

The bar is empty except the bartender.
The bar is empty except for the bartender.
The bar is empty with the exception of the bartender

Could you please to tell me 1. if all of those sentence are correct in grammar? 2. if the phases or words “except”,"except for"and "with the exception of " can be used exchangeablely? 3. if they can’t be used exchangeablely, under what situation each one of them can be used?
Thank you. I am hoping not to bother you so much

No 2 is correct

2 and 3 are both correct, but 1 is grammatically incorrect.

Offhand, I can’t think of a case where ‘except for’ and ‘with the exception of’ cannot be used interchangeably, though I wouldn’t be surprised if someone were to point out an exception!

It’s no bother!