Check out trekking bars for more hand position (won't have to change brakes). They are really comfortable for a lot of people and are only $22.99 at Nashbar right now. I have a set on one bike and they are indeed comfortable with several good hand positions. Also, Banjo Brothers makes a very nice waterproof handlebar bag for less than half the amount you mention (see it
here). SKS fenders are under $50. Bags that aren't waterproof are fine. Just put what's inside of them in large ziplock bags or other plastic bags. I like using toe clips with regular shoes. I just carry flip flops too. Your $300 should be enough to make sure your bike is in order if it has been cared for.