I will TRY to answer your questions.

1. Some feel the lower level growth is unproductive and actually take energy away from the productive upper branches. Some also figure it will lead to fuller and bushier plants. I don't really have a personal opinion on it.

2. Certainly, it stands to reason that crossing two super hots will give you a hotter pepper than crossing two mild or a super hot and a mild pepper. I don't think there is a chart that will tell you which combinations will result in in specific traits to the child plants. It is more of an inexact science of cross breeding to produce desired results.

3. Pepper varieties originate and thrive in various areas. Some are very hot, some hot and humid and others not so much. In general, the Chinense species will tolerate more heat than say Annuums or Pubescens. There is also variance within the various species.

4. Peppers do well with extra Nitrogen during early stages of growth. Increasing potassium and phosphorus and reducing Nitrogen is generally considered beneficial when a pepper starts to put out blossoms.

5. If you plant multiple peppers close together, they won't die normally. One or two might wind up getting crowded out but several can coexist. Keep in mind they will all be competing for water, nutrients and sun and will therefor not produce as well as those same plants spaced out adequately.

6. Peppers probably won't die in shade, but they are sun loving plants and again will not thrive as well as if they got significant direct sunlight. Some require more than others, but in general, they are sun loving plants.

I hope that helps. Good luck.

Bruce