I've had 3 back surgeries, I have 2 level fusion with rods and screws still in me. The answer to your squat question is, only you will know. I personally do the squat machine and have done as much as 700lbs for a few reps and I go all the way down, non of this half shit. I would not even try regular squats, but Im 50 years old too. So forget about the ego and get the surgery, do the rehab and listen to your Doctor,I mean I think the Doctors had to go to school or something like a home study course, right. Use test during the recovery and your surgical wound will heal faster. I was good to go at 4 months using test last time, without it it was like 9 months, big difference. Good luck to you, see if you can get to a pool to, pool exercise will be good for you in the beginning.