Your iPad was actually charging when connected to the USB port. It might have said "Not charging" but it was, just not as quickly as it would have through a high powered USB port or the AC adapter that came with the iPad. As far as not being able to connect to Wi-Fi, who knows why you couldn't connect, but I never had a problem getting mine to connect right away.
Technically you CAN do ANYTHING you want with your iPad as soon as you buy it. It's just the closed-source nature of the product means it's much more difficult.
Technically, you aren't buying the apps from one source. Picture the AppStore like a shopping mall. Yes, you can only go to that one shopping mall, but the mall has a wide variety of products for sale and has a team of people that make sure the products are worthy of selling. The AppStore actually makes it easier, because now instead of software developers having to rely on Google to come up with their website when the customer searches for the product they want, now the customer can just select a category of products that want to look at and freely browse through a list of what's available.
Don't get me wrong, I'm not a big fan of iOS, I'm probably one of the people on this forum who dislikes it the most, but I still recognize that it's not a completely terrible product and is excellent in many ways.
I think you were expecting a computer when you bought your iPad. Think of it more like you would a video game system. You have to use Playstation specific video games on a Playstation, and you have to use their operating system to play those games. That doesn't make the Playstation bad though.