I've done a bit of bike touring both on and off road(rail trail). I'm also an ex bike mechanic. All of my bikes are '80s-90's vintage. One plus to that is they are not the theft magnets of newer stuff.
Most modern early '90s on road bikes here in the US are very sport (Race) oriented unless you have a true touring or hybrid bike. Not enough clearance for tires in the frame or brakes. Also they are short and get squirrely with a load.
For touring you need comfort and durability and the ability to haul gear. Everything else is fluff. Older mountain bikes with triple chain rings and 7 speed rear cogs are very durable and give you the low gears for climbing hills with weight. Make no mistake on a loaded bike you will be going up like a Semi truck. Slowly in a low gear.
I suggest a 1.5 to 1.75 tire for mixed road and light trail use. Talc (baby powder) the inside of the tires and the outside of the tubes so they seat perfectly. It's nice inside your shorts as well to keep down chafing.
Make sure your rim strips are in good shape with no spokes protruding.
Get your bike well tuned and make sure your wheels are tight and true.
Carry chain lube and spare tubes and a patch kit. Also just a few tools and some way to inflate your tires more that once. Pump, several quick fills.
Front racks should be low rider style to keep the weight as low as possible. The lower the weight the better the bike will handle.
I like a sprung seat like a Brooks Champion flyer. Pure luxury!
http://www.wallbike.com/brooks/saddles/brooks-champion-flyer-special-saddle
That site sells a good bit of nice touring gear.
You want a handlebar that gives you mutiple positions.
I like old school Grab-On brand grips or maxi pads. They don't move when glued on and are cushy and grip well in the rain.
Make sure you have good heel clearance on your rear paniers and that the racks are designed to hold the weight you put on them.
Upgrade your brake pads to some good sftermarket pads like kool stops or Aztecs if you are usings '90s vintage MTB brakes.
A little bit of reflective tape goes a long way for safety while climbing slowly on busy roads.
Hope this helps some. Remember your not racing on a loaded tour. Enjoy the ride. Be comfortable.