A. If you add compost you wont really need anything more. I am sure some others have their favorites to add but the backbone is the “black gold” of the compost. The amount of compost depends on the organics in the soil to begin with. This can be judged oftentimes by soil color. A very light color usually indicates very low organics and I would add about 50/50 compost with the soil. If the soil is darker then you can add less. I would make raised beds. You can do this without sidewalls.