Yeah, thanks for the unhelpful smart assery. I know I can just google it and come up with a metric crap ton of sites of dubious value. I'm asking people who actually know what the hell those plans represent what is a good idea and what is not.
See OP for first question, 4-5 ideally with modularity for more. I'm not sure about the HOA. I was told when buying the place that there was not one, but then some random lady from down the street came to the door and said she was HOA president. But that there were no dues or obligations placed on the community. I dunno if she's a crazy lady with delusions of importance, or if there is some sort of stealth HOA I don't know about that doesn't actually seem to do anything.
If there was an HOA it would have come up in the deed search at closing. If you were sold a house with deed restrictions and they didn't reveal that at closing, you can sue the snot out of alot of people. Most likely there is some kind of loose community organization with absolutely no power, like a community watch, or she's a batshit crazy nosy wench.
I say build the coop. Find some plans and do it. Skip the truck cap solution. Building a nice coop will give you more experience and skills to expand on in the future.
Here's plans for a real nice one at instructables
http://www.instructables.com/id/Backyard-Chicken-Coop/