Hi Jelsis
I am not an authority on orthopedic surgeries, however I would like to reply to your post as I see some of your concerns and frustration.
Typically X-rays do not show much soft tissue damage (if any). The only thing an X-ray would pick up in this situation is an avulsion fracture, which is when the bicep tore did it take a piece of bone along with it. AnMRI is the imaging tool of choice to show soft tissue damage. In this situation it would give more information regarding the size of the tear, location of the tear and so on. In my opinion the imaging is not needed to diagnosis the bicep tear, as it is a very obvious dysfunction, however it may give the surgeon more information in preparation for the surgery.
I can also see you have some concerns regarding the length of time from the date of injury to the surgical date. I do not feel that it is a big obstacle so long as your husband keeps moving that arm. I would not recommend him relying on a sling 24/7. I would recommend gentle range of motion exercises so that scar tissue proliferation does not become an issue limiting mobility down the road. It might also not be a bad idea for your husband to see a PhysioTherapist before the surgery in order to keep things moving and balanced.
The good news is that this is a fairly 'routine' surgery and people usually recover very well and regain virtually 100% of the extremity function.