It's always a good thing to find the cancer early. You need to emphasize to his doctor that you want to be fully informed of every treatment option: from active surveillance, to surgery, to brachytherapy, to external beam radiation, and so on.
There has been a lot of discussion here lately about active surveillance (AS) for low-risk cancer found early, and it's generally felt that many urologists are not doing a good job of acquainting their patients with the AS option, so you might want to press him on that point.
I myself had surgery, but my case was a bit more advanced than your father's; also, my prostate was quite large, which ruled out brachytherapy (seed implantation).
I think you'll find there are many treatment options, each with excellent success rates. Now's the time to read, read, read and study those options to see which one best suits your father's particular situation. You'll find men on this site who have experienced all the various treatments, and all can share their experiences and offer their suggestions. Also, seek out the very best physicians you can find, no matter which treatment option you eventually choose. You want to make your first shot at this a good one.
Your local library probably has many, many books on prostate cancer and its treatment. You can also find at the top of our topics page a list of books that members here have found particularly helpful.
Good luck. I'm glad you found this site.