I don't use a heat pack unless the temp falls below those range. I'm much more concerned with overheating in the insulated container than it being too cool.
I never use cold packs. They aren't much use since they melt quickly and leave your animal in danger of overheating. I will put cold packs in the box for a couple hours before shipping though if it'll be hot at night to cool down the box.
I agree with Deborah for all of your other questions but would add:
I use packing tape to securely tape the packing label down and it works great.
I also drive to a hub for deliveries to minimize the time the animals spend shipping. I actually go straight to the World Shipping Center at our airport so I have a 7:30pm drop off time and they go straight on the plane. If you have them picked up instead, keep in mind that they will spend several hours in the back of Fed Ex truck during the hottest part of the day.
Also, I always request my buyers to have their animal held for pick-up at their closet hub instead of doing delivery whenever possible.