To answer a few of your questions about the procedures...
The reason he was checking your eyes was to determine neurological deficits, nerve impingement in the C-spine can lead to deficiencies in the way that you receive information to the brain (eyes, ears, mouth, nose).
Secondly, the generally accepted practice is to do 3 times a week for the first couple of weeks to take care of any acute injury. After that time period many chiro's move down to 2x a week to help care for the chronic injuries and lead into a wellness care. After the injuries are beginning to subside, many will go to a wellness plan that generally moves the appointments to 2-4 times a month. However, this is completely dependent on how well your body holds and adjustment and how quickly you re-subluxate your spine.
The reason that the chiropractor wants to see you beyond the injury treatment period is to keep you on the right pathway to health and wellness. You do not HAVE to see a chiro indefinitely, it is just many peoples opinion that they like the results they are getting and they don't like how they feel without care once they have felt how good they can feel.
I personally get adjusted once a week and can't imagine life without it.
As stated earlier, if you have a problem with the price, you might be better served trying to find an insurance based chiropractor to lower your out-of-pocket costs.
I hope you continue to use the chiro, the stress on the tennis court will really put a strain on your spine that will translate to your everyday life. Good luck!