TOPIC:

You can drag a group of walls (if I understand correctly) using:

Edit tab in Ribbon bar, Edit Building Group - Extend Current Floor This allows you to draw a selection rectangle around a group of walls and drag to a new position, retaining the wall connections.

See here

There are wall placement tools to place a wall at any angle, but you may find it easier to construct guidelines first, and then snap the wall to the guideline. The wall placement and guideline tools work on the same way. You can see the guideline tools demonstrated here

Suppose I created a front section shape (such as the building wizard)
How do I drag L2 say to the right, so that both L3 and L5 follow? When I select L2 it gets detached from the rest of the building.

How do I rectify walls to be at:
1/ 90° angle
2/ any definite angle, say 55°?

Thanks

Ref: