Does having brain surgery make it more likely that I will have a stroke later?

No. Having a craniotomy does not independently increase your risk of stroke later on. The risk factors for stroke are not influenced by surgery. If your reason for surgery was a stroke, a neurologist can counsel on risk modification strategies.
No. Stroke are a result of blood perfusion issues. If you have recovered from brain surgery, the issue of blood flow to the brain should not be an issue, but you should discuss your specific case with your neurosurgeon.
Answer. With any surgery there's a possibility of complications: that's the reason there is an observatory period to monitor the patient vital signs after a procedure.