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Blood meal, which is essentially dried blood, is used often in the garden as a fertilizer that add nitrogen to the soil (https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/blood-meal-fertilizer.htm), so using it is helpful in the garden.

There is one thing to consider though. With blood meal, you can have issues with animals being attracted by the scent and rooting around where the blood meal is spread. With undried blood, this issue will be even more likely as it will have a stronger scent.

This article should help: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/how-to-improve-clay-soil.htm

Many home & garden centers sell mushroom compost. There are also numerous online vendors. Here is an article that you may find helpful: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/mushroom-compost.htm

Amounts vary for compost use, and it is possible to use too much. However, an application of about two to three inches of worm castings to your soil as a top dressing should be ok.

This article should be helpful with your upside down gardening: https://www.gardeningknowhow.com/edible/vegetables/vgen/vegetables-grown-upside-down.htm

That is what mushroom compost can look like. Mushrooms can grow in manure or on decaying wood or both, depending on the variety. When you get mushroom compost, you are essentially getting these substances after they have been well rotted during the mushroom growing process.

Drywall has fillers and binders, in addition to the gypsum, probably stuff you would not want in your soil, such as fiberglass and adhesives.