You do not have to inform your supervisor of your specific appt. You can just let them know that you have a medical appt. that prevents you from making the meeting. The Americans with Disability Act (ADA) and HIPAA back you in that matter. The ADA protects you from any type of reprisal from your managment team for not making the meeting. It seems that you're not worried about anything other than just not wanting anyone to know. Your private medical info, is just that...private.
I have just started this process. I had my initial meeting with the doctor on Tueday.. I had a co-pay, but no other charges. The Nutrician/Dietician is $75 for the first vist, $40 for the next two months....as I have to show a three month supervised attempt with them. There is/was no $1000 fee though. My insurance cover on 85% of the cost, but I would assume I would pay that prior to the surgery.