MMg, Welcome to ATP!
I've looked at your two pics and see a few trunks coming out of the soil with their assorted branches. Are they all connected under the soil? I'll be tempted to separate them if they are not and pot each into other pots. That way you can see the branches from one trunk and prune accordingly. With one trunk you can at least cut all the branches off that are below a certain height so that you can have more of a single trunk with it's associated branches of one plant.
Easier to see/contemplate the look you want to achieve as you visualize which branches to prune.
Also cutting main stems just encourage more branching which can lead to too many branching arms.
I wouldn't prune all new growth as you want to have some sort of symmetry of branches to go with your, hopefully, thickening trunk. I would prune all of what I call "extraneous" branches, those that aren't adding (or important) to the general shape of the plant. Usually I look for "matching" stems (could be across from each other or staggered slightly, depending on growth pattern) on either side of a branch and anything growing between that would be pruned off.
Most bugs or their secretions should be visible to the eye and treated accordingly. Branches may wilt from lack of water and shrivel. I think it best to water deeply instead of frequently. Sudden low temps can cause freezing of moisture within the branches and leaves which will cause parts of the plant to shrivel and fall off.
