Which is better? If you opt for foliar feeding, does that bypass the problem of nutrient lock in the soil?

No, solair feeding is way less important then soil feeding. As for soil feeding you feed the roots and they dispearse it qually throughout the plant. It's ok to solair feed but from my perspective just not worth i. If your going to do it do it at dark hours.

You cant give the plant everything it needs by foliar feed alone. You can however feed a plant by the roots alone.

From what I know, the only things plants can absorb through their leaves are light, and air (a.k.a. CO2). However, misting the leaves, and maintaining a proper humidity level will help a plant retain moisture.

They can absorb nutrients in through the leaves but not all of them.

Also dont foliar feed in flowering as it can cause bud rot, which is a shitter