Yeah...here's my thoughts. Why get locked in only on one brand so soon when you are still a novice at what to take along? I'm ASSUMING a Dawes from Bikes Direct. I'm also assuming it's the Dawes Lightning Tour on the link below. Why?
A MUCH better choice for "touring" would be one made from good old fashioned Cro-Moly Steel! The Windsor Tourist (2nd link) will have a larger rear cog for better hill climbing. Or for a few $$$ more - the Motobecane Gran Turismo. 3rd link. Why steel? Steel has a "flex" to it that bounces back & absorbs road bumps & ruts. Aluminum, Titanium & Carbon Fiber do not. In short - for "touring" - Steel Is Real!
Panniers? Go as big as you can with as much quality as you can afford. Your life will be basically stored inside. You want "water proof" not simply "water resistant". If you have the room & the budget - a smaller front rack and small panniers for emergency medical supplies, personal grooming needs, etc.
What makes me so sure about steel? My "touring road bike" on 4th link. $1,200 & smooooooth.
you can pick up some panniers for 30 bucks for low end models...my friend bought a dawes,its a good bike but when he got it, he pretty much needed a whole tune up, especially his wheels they were so out of true,but could have just been a fluke..just make sure your bikes set up 100% properly,as most bikesdirect bikes dont come rideable outta the box..once he got his bike tuned up it rode exellent...600 miles is a pretty decent ride so just prepare for the worse and youll be fine..bring an extra tube and a mini pump just incase..and learn how to change a bike tire if you dont...also make sure you buy the right size dawes.
Bike fit is extremely important for rides that last more than a few hours. First make sure the bike size is right for you and then plan to spend about $125 to get a professional bike fitting at a local shop. There are several different ways in which the bike can be adjusted to fit you. It's worth it.
Don't get a soft bike saddle. Get a firm one. I know this is counter-intuitive, but ask around at your local cycling club, making sure you are talking with people who are actually riding long distances, not rookies who are thinking about it.
i;d say be sure you can ride a few hours on the bike you will be riding abroad
you need to have some butt training and saddle adjustment sessions
otherwise your first week will be painful