In planting our garden, do I need to not plant so deep? I usually plant about 2-3 inches into the soil. Do I need to plant more shallow, deeper?

Yes you can plant too deep! It depends on your seeds and your physical soil structure.

Normally many farmers plant their seeds up to 1.5 to 2.0 times the diameter of the crop's seeds. Now some seeds like lettuce need more direct sunlight and moisture, than say corn seeds that can be planted several inches in the ground with very little problems.

I've noticed that if I plant some seeds (like beans and cucumbers) in mostly compost, they do fine. While other crops can't germinate unless they have more soil than compost.

I sometimes use thin strips of newspaper or toilet paper to cover and help germinate some stubborn seeds in mostly composted soil in my no-till garden beds. The thin paper supplies extra carbon foods for soil microbes, while keeping moisture and more darkness around the seeds.

Hope that helps!
Happy Gardening!