What is the best and most effective way to root an avocado pit?
This article will help you: https://www.gardeningknowhow.com/special/children/sprouting-avocado-pits-how-to-root-an-avocado-seed.htm
I live in Atlanta, Georgia. I have grown an avacado two feet high. Does it shed its leaves when it gets cold?
Typically they do not, but if they do, it does not mean that it is dead. It may be just going dormant to protect itself and will regrow the leaves in the spring when it gets warmer.
Avocados cannot survive in temps below 20F. If it is colder than that for you this year, the tree needs to be brought inside or somehow protected.
I know that you've said that a baby tree will not live through a Canadian winter, but will a tree over 8 feet live?
Due to their sensitivity to cold weather, I would have to say no, though in a container the tree could possible spend summers outdoors. These articles should help: https://www.gardenguides.com/99621-grow-avocados-canada.html, https://www.gardeningknowhow.com/edible/fruits/avocado/avocado-tree-growing.htm, https://www.gardeningknowhow.com/edible/fruits/avocado/indoor-avocado-plant-care.htm
Should I remove the brown skin off the pit to root?
This article should help you with that: https://www.gardeningknowhow.com/special/children/sprouting-avocado-pits-how-to-root-an-avocado-seed.htm
I have a 5 yr. old avacado tree, approx. 30 ft. tall - healthy and thriving. It's getting too big, so we want to top it. Want to know if taking off 8-10 ft. right off the top would devastate the tree? Can you advise how to proceed?
This article will help with pruning your tree: https://www.gardeningknowhow.com/edible/fruits/avocado/pruning-avocado-trees.htm
I have a couple of advocado trees and wish to know how far apart to plant them and what time of year is best for planting.
The spacing depends on the variety of avocado you will be growing. This document will help you figure spacing for your variety: http://www.avocadosource.com/Journals/ITFSC/PROC_1976_PG_54-57.pdf Spring and early fall are the best times to plant them. This article will help with that: https://www.gardeningknowhow.com/edible/fruits/avocado/avocado-tree-growing.htm
I rooted and potted an avocado seed and when it reached about 12" tall with a few leaves on top, I pinched it back to about the 6-8" level just above another leaf nodule. I read that this will make it produce more/better growth. This was about a week ago, and so far, I haven't seen any more leaves -- so I'm wondering if I have harmed it by pinching it back. Should I just be patient or give up and try again with another seed?
I would be patient. You should see swelling on either side of the stem at the top of the leaf node point in a bit. It is not quite active growth season, so it may be a bit slower to grow. As long as the plant is alive, it should be fine.