Yeah, don't over think it. Just walk into a shop, buy some chain oil. If you are riding all the time, you probably want to oil your chain fairly regularly, like once every two weeks or so. It's been dry and dusty out there. Use a rag, put lots of oil on the chain and then spin the excess off with the rag. Don't forget your derailluer pivots. As for water, the only real area you will run into trouble with it the bottom bracket. If it's creaking, it probably means you got water in. Even with sealed bottom brackets, they get wet. If you are washing your bike the one thing you should make sure you do is turn your bike upside down and shake the water out. I have had countless bikes, caked in mud, soaked with high pressure hoses and yes I've had to replace the odd BB, but you know, whatever, it's a part of hte sport.
Other than that, bike are made to be ridden, enjoyed and broken. Chains stretch, brake pads wear. It's a part of riding. Enjoy it. Don't get hung up on it. It's huge that you are out putting those kind of miles in. Really fantastic. Keep it up.
