1. Can you explain me which slide element that you refer to? In this case, you may need to use CSS code to achieve that.
2 & 5. May i know what kind of edit or change that you mean on this thing?
3. Can you tell me which slider that you use? Maybe on several slider you can’t using full image without cropping.
4. May i know which thumbnail size that you want to edit and what thumbnail size that you need?