Crescendo, just read the thread of e-mails and you have already received a ton of great advice. Let me confirm some and add some. I have done many self-contained tours in the U.S., Europe and New Zealand. Here are some of the things I have learned.
1. I agree with the comment about a mirror. I can't believe that more people don't recommend it. In my mind, a mirror is seoncd only to a helmet as it concerns safety. You can especially see situations occuring before they happen, like a semi coming from behind and an RV coming in front of you, and little space for you on the road in this scenario. I have gotten off the road several times to let things pass.
2. Cycling in the rain. Staying warm is the most important in the rain. Gore Tex is the best I have found in a cold rain. In a heavy downpour I have found my state of mind to be my worst enemy, just thinking about all my gear getting wet, and sleeping in a wet tent in a damp sleeping bag. When this happens, I just resolve to pay to stay in a motel where I can get a warm shower, and know that I will be warm. It makes such a difference during the ride knowing I will be completely dry in a few hours. And I agree with the comment about fenders. It can make a big difference in an all-day drizzle.
3. For repairs, first take duck tape. That can fix a lot of problems in the short run. Second, I cut out relevant chapters from bicycle repair books, because I am such a klutz at bicycle repair. I obviously can change a flat, but I can never change a spoke without refering to the book. Also, take extra spokes and make sure you have the right lengths. And tools, including a chain link remover. Check with your bike store for a suggested list of tools.
4. No one has talked about gear. You ususally get what you pay for, so I think this is one place to spend the money. You can go to other forums for ideas and opinions about panneirs. REI and Adventure Cycling have good deals on high-quality panneirs, but they don't have a full selection. Also make sure that you have high quality racks in the front and back. Nothing like a rack bending and breaking in the middle of nowhere.
5. And you didn't mention the kind of bike you're cycling. For what you're planning, I would defintely buy a touring bike, although others may have different opinions. REI has a decent low price touring bike at aboub $600-700. At about $1000-$1200, Trek, Cannondale have good bikes. I have a Trek520 and it is an awesome touring bike. At about $2500 you move into another class. Waterford, for example, has a fabulous touring bike at this price.
Sorry to be so long-winded. Hope this helps.