Is it okay not to have surgery for a chiari malformation if there are no symptoms?

Absolutely. A chiari 1 malformation is not a dangerous condition. It is usually found incidentally during the workup for a headache. The only reason to have surgery is to relieve symptoms, and often the symptoms and the chiari are unrelated so surgery doesn't help. If you do not have symptoms, then you absolutely should not have surgery.
Yes. Chiaris occur in many patients. If you are asymptomatic, you do not necessarily need surgery. However, if the chiari has caused other imagng abnormalities (like a cyst in your spine), you should consider surgery before irreversible injury and symptoms appear from the chiari.