Hey everyone,
I just bought a few Meyer lemon trees yesterday. They're probably about 2 years old, around 2 feet high, very full and very green. Today, I repotted them from their nursery containers into 8" terracotta pots. They were VERY root bound (roots had grown into the shape of the nursery container at the bottom, nothing but a solid mesh of roots). Due to this, I couldn't actually get them into their new homes because the sides of the terracotta pots were more tapered while the nursery container walls are straight/square. Additionally, two of the trees had their roots more or less liquefied at the bottom (I guess from where the nursery had kept them overwatered).
Therefore I decided to amputate: I trimmed the roots by about an inch off the bottom until I hit healthy roots and could fit the plants into the new pots.

My questions:

1) Two of the plants are actually too full- they both have one or two branches that grow straight off the lower part of the plant horizontally by about 2 feet (so they're about as long as the vertical leader). Given the trauma I have just inflicted on these plants by severing their roots, when can I safely prune these? On one hand I am thinking I should wait at least a month before I revisit pruning them, on the other I wonder if it may even be better to prune them now since that would take some of the "load" off the now reduced root base. Thoughts?

2) I'm new to pruning so I am trying to learn but I suspect the reason these branches grew so long horizontally is because how they were pruned:

(Horizontal view)

(View from overhead)

By cutting the branch when it was growing vertically, I think it encouraged these horizontal offshoots. Do you agree? Is there any recovery from this? When I cut the horizontal offshoots, is there any way to cut them to encourage vertical growing?

Thank you for your help!