You don't want to put anything more then just a handlebar bag on the front of the bike, and in that bike you keep lighter weight stuff. Jandd makes a pretty good one called the Touring Handlebar Pack 1, it comes with a map case on the top and has 828 cu in of interior space, its not as watertight as a Arkel but it cost $110 less! You should do this in your rear bags too, if you don't want something to get wet put it into a ziplock bag just to be safe.
The weight distribution thing won't be too critical because you're packing light for a cross country trip, so to have 30 pounds on the rear and another 5 pounds in the front you'll be fine, but I wouldn't put more than 5 pounds on the front.
The ideas about the Deore derailleur and the crank are solid ideas if climbing hills is a worry for you..
Not sure what tires you're wanting to use but the best touring tires for lighter touring is probably the Vittoria Randonneur Pro and go with a 700 35 which should fit since your bike came stock with 32's, see:
http://www.amazon.com/Vittoria-Randonneur-Pro-Road-Tire/dp/B00TWQ7DOY. Also this tire is foldable so you could easily carry a spare in your bag if you're concerned about losing a tire somewhere west of Bumfalk, S. Dakota where people have pointed ears and can't understand what you're doing on a bike. These tires are well known in the touring world, the Panasonic Gravel King is not as of yet but they do make good tires; if you don't plan on doing any off road stuff or long distances on gravel I don't see the point, besides I ridden on gravel with less capable tires then either of those and never had an issue.
If flats are a concern for you Panaracer (Panasonic) makes a non replaceable tire liner called FlatAway that is lighter than a Mr Tuffy but is tougher than a Mr Tuffy by far! And because it has a sticky back you can place the Flataway liner into the tire and not worry about it moving while you try to install the tube, but it's this sticky backing that makes it all but impossible to take it out of a tire and put into another.
http://www.chainreactioncycles.com/us/en/panaracer-flataway-puncture-protection/rp-prod54140
Your bike has bosses already for pannier rack, you don't need to connect something to your QR to do this, besides I knew a guy who tried this on a touring trip and the fastening system for the rack broke while touring.
Obviously make sure the bike is completely tuned up and any even remotely questionable items replaced. Make sure you have some spare parts like a set of brake pads, Fiber Fix spokes (these are easier to use on the road then a real spoke) see:
http://www.amazon.com/FiberFix-Emergency-Spoke-Replacement-Kit/dp/B001GSMQZC ,chain lube, two spare tubes, flat repair kit of course, and don't forget a good mini tool like the Park MTB2 if you don't already have one, this place has the best price:
http://www.pricepoint.com/Brand/Park-Tool/Park-MTB-3-Rescue-Tool.axd. Make sure you tell your LBS exactly what you're going to be using the bike for so they can understand the critical nature of making sure the bike is completely ready to go. Once you get the bike back from the LBS take the bike on a 50 shake down ride to make sure they didn't screw something up, you don't want to find that out a 50 miles into your trip.
Look into adding a third water bottle carrier to the underside of your down tube; see this:
http://www.amazon.com/Minoura-bottle-holder-BH-95X-Adapter/dp/B009GIH07I Make sure there is room, usually there is enough room for at least a small bottle. Anyway the mount mounts to your down tube then a cage mounts to it.
You have a nice bike, you don't need a lot to get it ready, you just have to decide from all our opinions what fits your needs the best.