I have a garden that I grew tomatoes in this season. They all got a fungus, except the grape tomatoes. I removed the plants and tomatoes. I want to know is there a way to clean the soil so I can use this area for planting again next season. Thank you.
In addition to rotating your crops, you may want to solarize the soil. This involves covering the wet soil with plastic and letting the sun heat it for a period of time. You can also spray the soil with a mixture of water and hydrogen peroxide. Here are two articles that should help with your sanitizing project:
https://www.gardeningknowhow.com/garden-how-to/projects/how-to-solarize-garden-beds-to-eliminate-garden-pests-in-the-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/using-hydrogen-peroxide-in-garden.htm
I tried to plant some veg in our garden last year but knew the soil wasn’t good enough but tried it anyway. So this year, I have dug the patches up and replaced it with cardboard, leaves, old veg cuttings etc. with rich compost on top. I need to add top soil apparently, can I use the old soil which is basically rock soil and very lightly grey. Or should I use a different type of soil on top to mix?
You should, definitely, use a different topsoil. You may need to solarize it, as well. These articles will help:
https://www.gardeningknowhow.com/special/organic/the-importance-of-soil-for-an-organic-garden.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/improving-garden-soil.htm
They are usually dozens of them in groups
Unfortunately, your photo did not come through. I am unable to identify the issue. This can be anything from insect pests, to eggs, to fertilizers. It would be very hard to say without seeing them, though.
This is our first season with a raised bed. This was in the soil underneath our green beans...
Those are called Bird's Nest Fungus! They are very beneficial to your garden. This article will give you more information: https://www.gardeningknowhow.com/ornamental/fungus-lichen/birds-nest-fungus.htm
My houseplants have a white, fuzzy mold on the top layer of the soil, despite using my dehumidifier and I am not overwatering.
You may need to replace it with fresh, new potting soil. If you have a plant that needs continuous moisture, you may not be able to avoid the mold. Sunlight helps.
You also may want to try a gentle, homemade fungicide described in this article: https://www.gardeningknowhow.com/garden-how-to/info/homemade-fungicide.htm
Here are some prevention tips: https://www.gardeningknowhow.com/houseplants/hpgen/preventing-mold-in-the-soil-of-a-houseplant.htm
How long will it take to do this and how long will it be till I can plant new plants and shrubs, not in a hurry I just want to know the process.
You'll need to determine whether your soil is just compacted or whether it's primarily clay soil or both. It takes a little work to get it loosened up and optimal for planting. If it's clay soil, there are some plants that can thrive in that environment. Here are three articles that will help you decide how to fix your soil:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/improving-compacted-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/how-to-improve-clay-soil.htm
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/plant-for-compacted-soil.htm
Plant labels will often say something like "does best in dry soils" (or moist/wet soils). But my yard isn't adjacent to a pond or anything that would keep it saturated. If it's rained recently, it's wet; if it's been a while, it's dry. But I'm guessing that when people say, e.g., "moist soils", they're talking about some feature of the site that doesn't change from day to day. What do they mean? I have clay soil, for the record. Thanks!
Wet soils will be near a water feature, and remain wet, consistently. Moist soils will remain slightly moist, or go from dry to moist often. Dry soils are xeriscape gardens that do not receive rains, or rarely receives rain (Think desert setting).
To learn all about soil, check out this collection of articles:
https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers