I will try and answer your questions, but please keep in mind I'm nothing more than a satisfied customer. I'm sure one of the ODGW staff will be by later in the New Year to give you some better answers than I can.
1) First of all, the War Artisan ships are really beautiful, so good for you! If I were just starting out I would probably go with those instead of metal ones. As for gauges and whatnot, the ones included with the rules are 1/1200 and 1/2400. However, in the download sections there are gauges for 1/3000, 1/2000 and 1/1000 scale. I would probably just use the 1/1000 ones without any changes to learn the system. If you want to be a purist though, you could just print out the 1/1000 gauges at 111% and have everything in your scale.
2) There's not an easy answer to this, because the rules are broken down into different sections and then there are the charts and ship sheets. The rules are about 90 pages, not counting charts and ship sheets. The rules themselves can be printed in black and white and, in my opinion, you don't lose anything. For games though, the charts and ship sheets are best in color. Personally, I ordered the PDF and not the hard copy because I couldn't wait to get my hot little hands on it when they came out. Having access to a printer that I can run copies on for free definitely helped me make that decision. As I bought the download, I don't know how ODGW handles buying the hard copy. Sorry, but I can't help you there.
3) The rules are broken down into sections, as I mentioned above. The "Basic Rules" section (that's what it's titled) will get you to gaming. Within that section, it's broken down even further into subsections like Movement, Sailing, Gunnery and the like. The rules assume that you have no sailing experience at all, and pretty much take you by the hand. Also, the sailing model in this game is specifically designed to make learning it as easy as possible. As with any rules, some sections could have been written a bit more clearly, but you can always get an answer here on the forum. It's easy to dip your toe in a little at a time until suddenly, you feel like a ship's captain. When I have run the game at conventions, players pick up the basics within a turn or so.
The nice thing about AOS gaming is that you can get started with just two ships. Be forewarned though; you're liable to find yourself wanting more and more ships until one day, you want to do something crazy like refight the battle of Trafalgar. You will need a different set of rules to run a large battle like that. Welcome aboard!