I have the assumption that plants grow more foliage towards the arc of the sun. With containerized plants, I assumed I could rotate it every week to help it develop more balanced foliage. Are the assumptions correct? Is rotating plants beneficial or harmful to the plant?
Rotating some plants while in bud may cause flower stem weakening and bud drop, as in Schlumbergeras. but generally, if the light source tends to be one sided, it is a good idea to rotate the pot. You can do this at any time, but if you use a schedule, you get the most balanced growth. I've even made my own rotators for my small windowsill plants, equipped with silent clock motors, that did one rotation per day. They ate batteries, though.
A suggestion for larger plants - get a roll-around plant stand or tray. It makes the job a LOT easier.
Absolutely...this will help them get a more symmetrical structure. But ideally, there should be enough light that plants don't have to bend. One way to do this is to make white screens that can free-stand and are placed behind your plants. This will bounce light back to their dark side and will help keep the house or patio cooler. Make panels with twoXtwo's and hinges. Find beautiful light-reflecting fabrics and staple material to your panels. Cover with veneer strips.