I have arnold chiari malformation type 1. I recently had corrective surgery. What are the possible side effects from that?

There are risks. With any brain surgery, there are risks or brain or nerve injury, bleeding, infection and even death in rare circumstances. Specific to chiari decompression, neck pain, CSF leak, and pseudomeningocele formation are also risks.
Not likely. If you were to have side effects, they should occur right after surgery.
See below. Main concerns with this surgery are bleeding infection and a leak of cerebro-spinal fluid. Side effects are, and should be. Minimal.