It sounds like your betta's gill is back to normal. That's good. I'm sorry I couldn't get your pics. A message says that they had been removed or deleted. How is your betta fins? My betta Tony had ripped fins for a while, but they healed. Your betta's fins should heal after a while.
About your Ammonia. With ammonia 0ppm is aways the best, but .25ppm could be easily elimanated with a few, small water changes. Do you have a filter yet? That will also help with ammonia.
Do you have an aquarium thermometer? They cost less than $2 at my local walmart and other walmarts I have seen. That is a good way to moniter the tempreture (preferably 75 - 80 degrees). Your heater probably keeps your aquarium at a stable tempreture when it is cold, but when it isn't cold it is a good thing to know what the tempreture is.
You will need to keep an eye on your ammonia levels over the next month or so. The first month (more or less) after you establish a filtered tank, your toxicity will rise, peak, and then drop. I don't have any good links, but read up on the nitrogen cycle (I think I spelled it right), it helped me alot. Hope this helps!