4. You have probably figured this out, but there is a chance (was it 25% ?) you can get a seed from a fruit tree. Simply chop it down with an axe. The seed can then be planted anywhere in the dirt. Actually, the trees should really drop a sapling instead..
6. That's a good idea. Doesn't even need to be as strong as the current lamps, just enough for a small area. The new crystal lamp could be reworked to fit this role. It requires relatively rare resources, so you would have to consider if crafting a lamp is worth it.