More air plus more surface, it makes sense that broken up weed gets a better burn. It doesn't make it more potent, but you get more smoke that way.

Only thing coughing ever did for me was make my throat sore.

I definitely think time of day and restfulness or lack thereof are factors on how the high feels to someone. I noticed a long time ago that getting high in the early morning produces a much different high for me than later in the day or evening. It's my favorite time to blaze and I usually do it right after my first cup of java.