I will take several exceptions to the OP's recommendations:
1. Giving any hard guidlines regarding how much fluid to drink is dangerous. In Texas, you would need quite a bit more than 2 bottles/50 miles on a summer day.
2. An out and back ride is no easier or harder than a loop. Many people, myself included, enjoy loop rides more than out and back routes. A better strategy is to map out a route that avoids difficult hills, passes evenly spaced convenience stores, avoids heavy traffic, has interesting scenery, etc.
3. Setting speed averages without knowing the rider is not a good idea. A better strategy is to use a herat rate monitor to determine ones exertion level for 80-85% of MaxHR and try to average this heart rate during the ride. The idea is to ride in a manner that conserves glycogen so a bonk is less likely.
4. You do not stress calorie intake except to recommend a bottle of gatorade and a couple energy bars. this is insufficient calories. A person who has done no more than 50-60 miles is a prime candidate for bonking on a long ride and should be taking in ~250 cal/hr.
Your basic premise that a person in reasonable conditioning can do a slow century is sound. And your recommendations regarding equipment, bike fit, and clothing are also good for century riding, as well as any riding.
Another recommendation for the novice century rider is to take frequent breaks and to stretch muscles to help avoid cramping. In hot weather, taking breaks at stores allows one to get inside some air conditioning to help cool the body down. This may not be a big deal in Alberta, but in Texas and most of the Southern US, heat exhaustion and heat stroke are serious dangers on long rides - especially for someone who has never done a century - as much of the riding must be done in the heat of the day.