Please fact check my understanding of exposing away from the noise floor!

[Liam Coleman]

I would love someone to fact check my understanding of exposure and exposing away from the noise floor to get cleaner images. 

1. ISO and Dynamic Range are linked. No idea why but they are (could someone help me understand why boosting the signal would effect dynamic range?)

2. Exposing a stop or two brighter is a good way to clean up the image and move away from the noise floor giving more latitude in post. 

3. Dropping your ISO is a good way to force you to let more light hit the sensor. 

4. In doing this you are playing closer to the upper limit of the sensor, it is compromising, due to the decrease in dynamic range in highlights (say a window).

5. Working in reverse. If you are shooting Hi-Key where there is plenty of light and you are well away from the noise floor. Raising your ISO and dropping ND is a viable solution to raise the Dynamic range where you may need it. (also what are some indicators you may want to raise your dynamic range? shooting hot sky?)

One more question, is there a lower limit on ISO you would go if you wanted no texture in the image at all and your not worried about clipping? or is it back to the compromise of dynamic range?

THANKS in advanced, so difficult to wrap my head around. Think i'm almost there.