Like you, I had radiosurgery - mine was gamma knife. I spoke at length with the doctor about it before it was done to get a better understanding of the possible side effects. I would strongly urge you to get in touch with your doctor and ask the exact questions you've posted here, because every case is different, and he (or she) knows your case best.
That said, I was told that with radiosurgery, yes, there will always be some swelling and they actually want to see that, because that's the body's reaction to the damage being done to the AVM, and damaging the AVM is the whole point of the radiation. I was told to expect swelling anywhere from 3-9 months which is before obliteration due to the radiation focused on the AVM and is part of the reaction to the damage being done to the AVM. I was told if I had side effects from the swelling I would probably need to take steroids for it.
I was told that they would do an MRI at 12 months and again at 24 months to see what the AVM was doing and how it was reacting to the radiation. My doctor said he likes to give it 36 months of observation; each AVM reacts differently. Sometimes an AVM can be obliterated in as little as 9 months after radiosurgery, and sometimes it can take up to 3 years. At the 3 year point, my doctor said if there was still residual AVM or if the AVM did not respond the way they wanted to the radiation, we would need to discuss what to do from there.
I currently have left ankle weakness which I suspect is from my AVM, and I was told that the weakness might get worse when the swelling starts, and then it would most likely get better, but I would probably need PT to get specific exercises to help strengthen it again.
From your post it sounds like you have a lot of uncertainty about the aftermath of the radiosurgery. Remember that you're paying your doctor a whole lot of money, and part of the care you receive from him is information, so don't be afraid to call and say you have some questions.