Without examining you and reviewing your imaging I cannot state if you are a surgical candidate, and cannot recommend a procedure. Based on the MRI description, your symptoms are not all explained by the MRI findings. I would ask the surgeon which symptoms are explained by your spine abnormalities, and could there be other causes to exclude. You may wish to see a neurologist before going to surgery for a non-surgical opinion. I would encourage you to seek an opinion from a large spine center to make sure that all medical and surgical therapies are available to you. Good luck.
Regarding your choice and back surgery. I have recently had a fusion at L5/S1 - I had very similar symptoms as you have.
I would have the surgery again - I had soooo much relief, however I was also left with terrible pain. This is because pain goes in layers when one has an injury or back pain - that is that the Dr's may get rid of the major pain, but that major pain was covering the other lessser pains. does that make sense to you?
I have since been having a therapy called Myofascial Injections - these injections deal with the muscle spasms and trigger points that were there before the surgery (but you couldnt feel them) or they can eventuate due to the surgery.
Just my experience for you - hope it helps, I know its a hard decision to make.
Also if you are over weight - get it off!! Stop eating root vegies, breads, cakes, pasta, and drink lots of water (gallons!)
Plus of course, no chocolats and no soft drinks (full of sugar)
Best wishes