You can disinfect town compost by putting it in heavy plastic bags and leaving it in the sun for several days. As long as it reaches 130 degrees or so, any mold, fungus or weeds will be killed off. Adding a shovelfull of soil will restore the “good” bacteria.
You can definitely grow potatoes from the store-bought kind so long as they sprout. Don’t need to buy seed potatoes from a garden center.
Compost should be damp enough to feel like a wrung-out sponge.
A slurry made of newspaper and water, spread around the roots of plants, will defeat cutworms.