Re: Pre-recording woes
Don't sweat knowing the songs yet. I have been in situations where we wrote the songs in the studio. You will have time once the recording is done to spend some quality time practicing along with the tracks. Another trick I have used is to get a drumless track from the engineer and play along with that.
As far as the engineer acting as a producer, remember it is up to the band to use or discard his advice. Don't let him bully you into making changes you are not comfortable with.