First, please note that the dates you are interested are currently not available at the best discount rate. You can still get a 15% off discount using an entertainment card or even just the DisBoards code which somebody around here re-posted again recently. One or more of the dates you want may become available at the "retro" rate that Hojo advertises. You will need to have the entertainment card or
Disneyland annual pass to use that rate. You can book the rate without having either of those things, but you will be asked to present the card at check-in to keep the rate.
You can buy the entertainment book for whichever city you want, including your own. I live in northern California, so when I was interested in having an entertainment card, I bought the northern California book from my niece who was selling them for a school fundraiser. You use the card that comes with the book. Books are also available directly from entertainment.com, some retail stores, and many other fundraising organizations. Alternatively, you can purchase just the card, from eBay for instance, if you think you won't be interested in the book. The current book and card are valid through Nov. 1, 2011. Books and cards valid after that date will go on sale sometime this summer. The card you have must be in date when you check in to the hotel.
You can make the reservation online or by calling. LKEP is one code that works for the superior discount if it is available. LNEP used to work for the 15% off discount. Usually, I find it easier to call in-house reservations directly when booking. The online system isn't cooperative when making a reservation that has special rates for only part of your stay.
If you are extremely averse to freeway noise, your best bet is Building 2. That would be a deluxe queen room or a standard king. Only rarely have I found the freeway noise noticeable while in Building 2. You definitely do not want a standard room or kid's suite in building 1 because those rooms are on the freeway side of the building, and that building is closest to the freeway. I have seen mixed comments about freeway sounds on the view side of building 1 and the rooms of buildings 3-6; your tolerance will depend on your noise sensitivity.