Having just been thru this exact scenario of how and what do you do for aeration I'll tell you what I did for my ponds. I have two ponds that are both about 1/2acre in size. Deepest depths are 12' in one and 10' in the other. Like you, I had a ton of questions so you are definitely in the right place for help.
After reading alot about different types of aeration the thing that stood out to me as being the most efficient and beneficial was a bottom diffuser system. I shopped online for weeks maybe even months trying to find a way to build one myself and save a bunch of money. All I accomplished was simply get my head spinning.
After more reading, probably the most important thing in my opinion is what are you using to move the air. From what I learned you need an oiless continuous duty rated pump just like Jevans stated. It will cost less to run, it's easier to service, and best suited for this type of application. My pump is a Brookwood 1/3hp piston compressor. Picked it up at a very reasonable price used and rebuilt from a reputable dealer of complete systems. This pump is rated 4.65cfm which is sufficient to provide the right airflow for me thru two 100ft runs of weighted air tubing. One run to each pond. I can even add a third line if needed.
To save money, I built my own manifold and box to house the pump. A little thought and some mechanical/building ability you can cut out some of the cost this way but it takes your labor and time. Something you'll need to weigh out benefit wise for your particular situation.
For the diffuser, I put one dual air station from Vertex in each pond. After everything I read, they seem to have a very sound approach to their product as well as good warranty and support. Smaller bubbles=Better.
I'm pretty sure your elevation will play a role in your pump sizing but a pro on here can definitely help you with that. Don't mean to sound like I'm pushin anything on you but Ted at Forever Green REALLY helped me understand this stuff when I decided that was the product and route I wanted to take.
You won't regret putting in a properly set up system, it really does make a difference.
