Set the Right Pace for Long Runs

To prepare for my race, the long ones will increase gradually up to 20K. Coach says, "The pace of these long runs should be slow enough so that you are not huffing and puffing at any time--even at the end. I recommend a pace no faster than 9:30 per kilometer, at a temperature of 14C (or cooler). It is always OK to go slower."
"The best run-walk-run ratio is 20/40 (run 20 seconds and walk for 40 seconds). The slower the long run pace, and the more liberal walk breaks, the better chance you have of avoiding aches, pains and excess fatigue. Even a pace that is 3-4 min/mi slower than goal pace will give you all of the endurance. Remember to watch the temperature and slow down by 20 sec per km for every 2 degrees above 14C."
Mr Galloway says, "On hot days, start early enough so that you can finish before the sun gets above the horizon, being aware of safety issues." Makes me wonder if he has any idea how early the summer sun rises this far north.
I realise I have no knowledge of how to set a pace for myself. So this was one of my first questions.
On the shorter long run weekends, Mr Galloway suggests running at any pace I wish, using any run-walk-run ratio I wish. In the race his initial suggestion would be to use 1-1 for the first 10K and either 2-1 or 1-1 for the last 6K. On these shorter weekends, Mr Galloway suggests practicing 1-1 and 2-1. We will discuss this more as I get closer to the race date. I have been trying a 4-1 ratio and it feels too easy. But my pace resembles a tortoise.
On long ones, whether walking or running, Mr Galloway suggests keeping a short stride, with feet low to the ground--as in a shuffle. Mr Galloway doesn't recommend power walk or race walk. It is OK to walk fast by using quicker turnover with a short stride through practice.
Eating a snack of 200-300 calories within 30 min of finishing a long one has helped his runners recover faster. Mr Galloway's website offers links to the specific products he recommends to promote recovery & fluid replacement on the day before and day after long runs.
Mr Galloway recommends taking a day of rest from exercise on the day before long runs. If you want, you can do non-pounding cross training on the other non running days (water running, cycling, swimming, elliptical, etc).
On the Tues/Thurs runs (30 minutes each), Mr Galloway suggests running at any pace and using any run-walk-run ratio that I wish. I will try the 1-1 and 2-1 on these short runs. I may also try the 30/30 on the short days.