I have grown Avocado trees from pits before, but this one has strange leaves.
There are several varieties of Avocado -- this must simply be a different cultivar than what you've grown in the past, or an Avocado that was the result of unintended cross-pollination, or the growing conditions are different enough that the plant is forming a bit differently. There shouldn't be any issue as long as the plant continues to grow, so have fun watching your Avocado experiment! This article may also help you: https://www.gardeningknowhow.com/edible/fruits/avocado/pollinating-avocado-trees.htm
My tree is losing its leaves they turn brown and fall off. What can I do to save my tree? The tree has some dead branches.
This is difficult to determine, not knowing if this is an indoor or outdoor tree, and the size of tree that you have.
This could be a number of issues, including environmental; exposure to elements such as sun and drying winds.
Changes in water; too much or too little.
Root disease or pests.
See if the trees branches have died off. Scratch the bark, if you see green it's still alive.
Here are some links with more information.
https://www.gardeningknowhow.com/ornamental/trees/tgen/tree-scratch-test.htm
https://www.gardeningknowhow.com/edible/fruits/avocado/avocado-tree-growing.htm
https://www.gardeningknowhow.com/edible/fruits/avocado/avocado-pests-and-diseases.htm
I didn't cover my tree last night and now it has frost on leaves. What can I do to before sun gets to it to stop the frost bite?
These links below will help you.
https://www.gardeningknowhow.com/plant-problems/environmental/tips-for-saving-cold-damaged-plants.htm
https://www.gardeningknowhow.com/edible/fruits/figs/cold-hardy-fig-trees.htm
So I learned that I could grow an avocado seed and I decided to try it out. It grew a root that's about an inch and a half long and I see a little sprout coming from the top of the seed. Well, I accidentally took off the other half of the seed while inspecting the seed. Will that affect the growth of the sprout?
It may or may not effect the little plant.
Here is a link to help refresh you on how to care for your little seed.
https://www.gardeningknowhow.com/edible/fruits/avocado/indoor-avocado-plant-care.htm
Over the trunk of my avocado tree I have found stains/spots or little areas of powder, very white powder. Is it due to a borer, or is it another disease? Many thanks.
I believe it is a type of fungus. If so you can treat with garlic mixed with water.
Avocados end up with lumps over the skin, don't mature and fall off prematurely. What can I do use to prevent this? Thanks, Heather
Have you seen the actual bugs or the eggs inside the fruit? A picture or description of what they look like would help with identification.
Otherwise, this visual guide to symptoms will help you identify the problem:
http://ipm.ucanr.edu/PMG/C008/m008fpfrtdmg.html
As this article describes, caterpillars, thrips, scale insects, and others can feed on avocado fruits:
https://www.gardeningknowhow.com/edible/fruits/avocado/avocado-pests-and-diseases.htm
I just transplanted 2 nursery bought avocados in flower. One has gone into shock. Should I remove all the flowers so they can better root themselves and recover?
Yes, removing the flowers is a good idea and should help the plant recover. Here is more about helping plants with transplant shock: