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Well, by far, the easiest way to guarantee a cutting is by taking new wood. This will mean that it will take a little longer to mature, but you can get much better success rates with new wood. This article will give you more information on taking cuttings from shrubs and trees: https://www.gardeningknowhow.com/ornamental/trees/tgen/how-to-root-cuttings-from-various-shrubs-bushes-and-trees.htm

Yes there is. This can be quite difficult, but with the right timing, and knowhow you can do this. Here is an article that will help you: https://www.gardeningknowhow.com/ornamental/trees/tgen/fruit-tree-sterilization.htm

I would not know how to protect against monkeys, as we do not have this issue in our country. Being as intelligent as they are I would say that just about anything you do will be outsmarted by their need for food.

I could suggest asking a local nursery about what they do when this issue arrives. Sorry I could not be of much help here.

It could be that it is lacking fertilizer, or has contracted a disease. Can you include a photo? This article will give you information on their care in the meantime: https://www.gardeningknowhow.com/edible/nut-trees/macadamia/how-to-grow-macadamia-trees.htm

Macadamias can self-pollinate to some extent with one tree, but cross-pollination greatly increases nut production, so it's best to have two trees. Bees are the usual pollinators, and it they are unavailable you will need to pollinate by hand. Here is some information about which varieties seem to self-pollinate better than others:
http://stfc.org.au/macadamia-tips

I am unsure to what the exact question is, but I will include a collection of articles that will give you more information; https://www.gardeningknowhow.com/edible/nut-trees/macadamia/