When digging in a place where a shrub has been before, there is sometimes white substance in the soil. Does the soil then need any treatment?
It depends on what it is. Some white molds are beneficial, and some are not. Unfortunately, your photo did not come through, so I am unable to see it to ID it.
If you are concerned, you can apply a fungicide. This article will help: https://www.gardeningknowhow.com/garden-how-to/info/using-fungicides-in-garden.htm
We just moved here have lived in S. Tx. all my life never had a problem like this. Love the new house but having a nice yard is driving me crazy. It is also full of weeds rocks and just awful clay like soil. What do I need to do?
You have your work cut out for you. You will need to add amendments to the soil to combat the clay and remove weeds by eco friendly means or with an herbicide. Raking can help remove much of the rocks. Or you can go with raised beds with new soil. Here are articles that should help:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/how-to-improve-clay-soil.htm
https://www.gardeningknowhow.com/plant-problems/weeds/post-emergent-herbicides.htm
https://www.gardeningknowhow.com/plant-problems/weeds/using-organic-herbicides.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/working-in-rocky-soil.htm
My plant is doing well in sand, but have trouble when watering with keeping sand in place. Can I add soil on top of the sand to steady my plant when I water it?
I don't see why not. It will eventually work its way down. To improve its fertility and composition you can add compost or rotted manure instead of soil.
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/amending-sandy-soil.htm
It affects all our garden plants until they eventually die.
The best you can do is plant resistant varieties. Verticillium wilt can live in soils up to 10 years. There is no product that can eradicate it from soils.
You can try covering the soil with clear plastic for several weeks. This works better in the heat of summer.
https://www.gardeningknowhow.com/plant-problems/disease/verticillium-wilt-treatment.htm
Our best recommendation is to remove any plantings from the area, get rid of any weeds and start over. Your extension service has some in-depth information about this problem that may be helpful: http://discover.pbcgov.org/coextension/horticulture/PDF/Lethal%20Viral%20Necrosis%20FAQs%203.2018.pdf.
I live in Mississippi with black swamp clay. I have Goats and Pot belly pigs. When it rains there pens turn into a swampy mucky 4inch thick mud mess. The water does not seem to drain away it ponds. What type of medium would be good to use to lighten the soil to drain?
You can improve the soil or it might be necessary to create better drainage by adding a French drain, for example. Here are some options:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/yard-drainage-problems.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/how-to-improve-clay-soil.htm
I had planted it in soil, but the container broke. So I decided to put it in water. Not in the water itself, but it has had some fuzzy (mold ?) on bottom. So I trimmed it off. Now it is doing nothing. Should I remove the bulb & place it in a brown bag to let it rest ?
I would start over with a new bulb. Were you trying to force it inside? By trimming the bottom you may have removed the source of roots.
https://www.gardeningknowhow.com/ornamental/bulbs/bgen/forcing-bulbs.htm