What's your question? Ask

Rust happens mostly because of poor air circulation in a plant. The best and most natural way to help with this is do do a little pruning to open up the plant and allow better air circulation.

Treating the plant with a fungicide will also help. Neem oil, which is organic, is an effective fungicide (and pesticide). Sulfur or copper based fungicides are also effective.

It sounds like maybe aphids or scale. Either way, the whole group of pests that affect plants are treated the same way. I personally like to use neem oil. It is organic, safe for pets and people, very effective and treats the plants for other issues it may have. Here is more information:
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm

These articles will help you:
https://www.gardeningknowhow.com/ornamental/trees/tgen/repairing-tree-bark-damage.htm
https://www.gardeningknowhow.com/plant-problems/pests/how-to-keep-rabbits-out-of-gardens.htm

It sounds like it is powdery mildew. These articles will help:
https://www.gardeningknowhow.com/problems/get-the-cure-for-powdery-mildew.htm
https://www.gardeningknowhow.com/plant-problems/disease/powdery-mildew-homemade-and-organic-remedies.htm

It sounds like a nutrient deficiency, most likely nitrogen, but it could be a micro nutrient as well. I would fertilize the plant with a complete, but nitrogen heavy fertilizer. You may also want to get the soil tested to better identify what the nutrient lack exactly is.

How you approach this really depends on what kind of shrubs they are, but you can prune back most shrubs by up to 1/3 per year without harming them.