This is my expertise and a huge portion of my practice. Asymmetry is normal and expected. Buccal fat pad gives slimming not symmetry. Masseter botox will make you slimmer and make the jawline more loose. Fillers help give shaping and contouring. If you want perfect or close to perfect symmetry...
No, there's no correlation between the volume of cheek bone and the strength/thickness of the muscle layers by, around or over the cheeks. Sounds like an urban myth. Cheek volume, as viewed externally, is determined by the amount/shape of bone and overlying subcutaneous fatty...
There is no cream or any other product that you could place on the skin of your cheeks to reduce chubby cheeks. This issue with chubby cheeks is not the skin, but the tissue below the skin and anything you place on top of the skin will not penetrate deep enough to have any effect.