I hope you have explored the discussion boards a little. So many of these questions are VERY frequent but are also very different from one person to the next. Two people of the same age and health can have the same procedure and recover completely differently. For your questions, I will answer them from MY experience, which is not typical or atypical, just mine.
Life/disability Insurance: You will likely still qualify after surgery as the surgery is a corrective surgery to reduce/limit Chiari's effect on your body and life. I would question your eligibility if it is independent insurance verses offered by an employer. For my employer sponsored insurances, I had to wait one year to be covered for existing medical conditions (Chiari.)
Surgery: Recovery can take from 4-5 weeks up to 5-10+ years. It's not a process to take lightly. The surgery in its least is very invasive. They make a 3-5" incision in the back of your skull/top of your neck. They then either cut through or move the muscle to expose the skull. They remove an approximately 1" piece of the skull to expose the dural sac (the part that covers your cerebellar tonsils.) If this is the extent of your needs in surgery, they will put in some type of mesh plate and stitch back up. This is the least invasive. I, for one, also had the dural sac opened, a patch grafted and placed over the opening. The back portion of my C1 vertebrae was removed. So, not to make it scary, but it is VERY intense.
Treatment: There are other treatments, but they all treat the symptoms, not the cause. They can treat things like headache, sleep problems, brain fog, etc. Surgery is the only corrective treatment, even then it's not guaranteed.
Whether you get it now or wait is a question you really need to sit down and talk to the surgeon and loved ones about. You should weigh your symptoms, the rate of progression of symptoms, and the recover as well as external factors in your life. Can you afford to take off work for an indefinite period of time right now? Do you have children that will require your attention and needs afterwards? Can you live with the symptoms you have now if they don't progress?
Keep in mind that even a successful surgery doesn't mean that it will correct or reverse any of the symptoms. This was made VERY clear to me prior to surgery. It CAN get worse or it CAN stop progressing. It's truly a matter of weighing your pros, cons, and the future.
As far as Chiari, it in itself causes very little pain. In reality it's generally the decrease spinal fluid flow or syrinx's or the increased intracranial pressure CAUSED by the Chiari (as my surgeon explained it.) Over time the increase of pressure can cause a loss of function (including the other things.) It was explained to me as wrapping a string tightly around your finger for a few moments and removing it quickly. Do this repeatedly and you're going to lose function and feeling in that finger. The same happens with the brain and pressure.
Please Please Please sit down with your surgeon and talk about all these things. If they won't sit down and talk to you about it, find a second opinion. Your surgeon should walk through these things WITH you, not just look at your anatomy and tell you what's best. I hope this helps! XOXO