Definitely Hypericum.
However Pic 2 shows a single flower on a stalk - that would be Hypericum calycinum or Rose of Sharon. Pic 3 shows clusters of flowers on one stalk, that would be Hypericum "Hidcote".
If in doubt, you can't go wrong in pruning just after flowering. 95% of flowering plants fall into this.
Hypericum will sprout from old woody growth, so you can prune as hard as you like, but generally take about 6"-12" off to give it shape and keep it under control.