To RE and learn a schematic you need the item bound to you. So, if you can't socket in something because of your level, you won't be able to learn the schematic.
Incorrect. You can learn schematics from freshly crafted unbound items. However, you can't learn a schematic from an item that has been crafted by another player. Putting a component into a shell and pulling it out again erases the crafter information, so a schematic can be learned from it.
Another case where pulling components out is relevant is if you want to use an alt to RE something only your main has access to. Endgame components only come pre-installed in shells, and are bound when you buy them. Thus you need to use a bound-to-legacy shell to smuggle them to an alt.