From what IÂve seen no, the stalks wonÂt re-grow from the top directly. TheyÂve been topped, and branch at the next node. The new growth has more leaves because none of them are stripped, though there is a thinner stalk in there somewhere.
I have no idea how long it would take a new branch to get as big as the main stem. But they do grow rather slowly, so if height is important to you, it might be better to go for the taller stalks to begin with. Or maybe go for a mix of heights to save some green.
IÂd guess that the wax is more for sealing the wound from the topping than inhibiting growth. My LBÂs werenÂt waxed, and they still branched below the cut, which now looks like a dry wood ÂscabÂ.
If you do buy some, remember to check that theyÂre a good shade of green, and firm without any yellowing on the stem. For bare root ones, see that the roots arenÂt brown or mushy, and they shouldnÂt smell.