The vast majority of your questions will be best served by first reading a text such as “Between Heaven and Earth: A Guide to Chinese Medicine” and/or “The Foundations of Chinese Medicine: A Comprehensive Text for Acupuncturists and Herbalists”. After a more than rudimentary grasp of TCM most of these questions will be answered and, if not, your questions will get more detailed. I don’t say this to off put your questions, just that it is very easy to literally talk in circles with Chinese Medicine unless both parties have a reasonable grasp of the underlying theories.
The general answer to your question is yes in the sense that you can always relate an issue to some aspect of the meridian organ system, but, no, as you don’t always follow that clinically. Physical trauma such as a acute bone break, for example, would be treated locally and technically is just a trauma and nothing more. But a practitioner will also at that time consider their overall health - so a break in a frail elderly person for example, the treatment would be for the acute break, but likely deeper for the kidney/water system as it is in charge of deeper vitality and bone health.
The five element system and the 8 principles overlap strongly - or the same syndrome can be explained using either set of vernacular in most cases. Some five element purists will discuss it more (see “classical five element theory” section), more TCM practitioners will use both somewhat evenly but in a different way than a five element practitioner might, other systems don’t exactly use them at all - but they are always there in the background of the practitioners mind. At the end of the day how you “explain” the factors that led to the persons condition are only useful if they help you treat them and if you can reliably on a broad range of people with a variety of conditions get clinical results.