unsure of what to do (medical issues PREOP)

Honestly I would schedule your surgery for a shunt ASAP. You can't mess around with your brain. You can do this surgery afterwards. I know this sounds crazy but 250lbs isn't life threatening. You have time to deal with that later. All the best. 

If you have the shunt and are able to lose weight then  you may not need so many revisions. Not everyone needs that many revisions

You should call your neurosurgeon. After the SW and dietitian you still need psych., then your file needs to be reviewed if your going thru TWH then it is the surgeon. You should at least touch base with neuro if your symptoms are getting worse

You already say that you are losing vision.  If everything gets moved forward at the centre, it will still be sometime before you lose a significant amount of weight, and by then you could lose your vision entirely.  I agree with Monica.  Your could call your centre and ask to be put on Opti now so that you can start losing weight now.  If you are on Opti and following the shakes faithfully you will lose even if you don't exercise.  Remember that the surgery is just a tool.  You will still have to work really hard after surgery, being careful what you eat and exercising.  Like the others said, call your neuro now.