...I have discovered that nutrition is an intellectual black hole. No one knows anything! It's very irritating and it makes finding a healthy diet very difficult.
Maybe you just haven't been looking? The reality is that there's a nearly endless amount of information on nutrition in addition to fundamental guidelines put forward by governments and NGOs based on decades and decades of research and discussion. All your questions are answered here: (simple google search for dietary guidelines)
Guidelines for prevention of heart disease and cancer, the two major causes of death:
Two specific diets which are held in high regard by the establishment right now:
In a nutshell:
The guidelines are a solid framework. Tweak as needed.
As far as CR-
I am *only* speaking from my personal point of view (and not on behalf of anyone else), but I think that CR is not something that can be done casually and without a degree of meticulousness and dedication. I would personally suggest that CR should be undertaken with strict monitoring of the foods you eat, the use of dietary software to track nutrients, etc. Otherwise you risk malnourishment.
For example, although we don't know about your specific anthropometry, your BMI implies that you should be cautious about a "calorie reduced diet." Any general practitioner you're seeing would take pause if you, as a patient, said that you wanted to reduce your calories. You are not overweight, and CR leads to weight loss. Consultation with your doctor as well as blood work are a must IMO.
There just so happens to be a wealth of information on CR on this very website (fancy that).