Wool pellets usually have a rating of 9-0-2. This is dependent on how dirty  the fleece is when it's sheared. It could be higher in nitrogen, so you don't need a lot to be effective. Wool also adds micro nutrients that help to feed your soil biome. It's also going to biodegrade and add organic matter to your soil. The pellets also swell up when they get wet, thus creating air pockets and improving aeration for the roots.

1/2 cup of pellets per gallon of soil. One 1 litre package will cover approximately 20 Sq ft of garden. I have seen videos of people dropping pellets into a row as they plant seeds, but I haven't tried that yet myself. I just added them to a potting mix and put seeds in the pot.  The pellets did make a big difference in growth.

Hygroscopic just means the wool holds water very well. Having the wool pellets means that water will be retained better, so you won't have to water your plants as often.

Yes, generally safe for pets.

Yes, great for houseplants and pots.

No, wool resists mold naturally.

They break down slowly over 4-6 months.

No, wool is naturally pest-resistant.

Light natural wool order at first, goes away quickly.

Wool grows just like your hair does. After a while it starts to get matted, full of dirt and itchy. It does provide great insulation to keep the sheep warm in the winter, but it really needs to come off in the spring. It gets longer and longer and it gets quite heavy. A fleece from one of my sheep is minimum 4 lbs, but some go as high as 10. It gets to be a lot to carry around.