Displaying only certain categories

On my sidebar is a list of Categories used but I was hoping to only display parent categories.

For example: If I have a category called SPORT and a subcategory called BASEBALL and SOCCER, can I set it up so that my sidebar only shows the parent category: SPORT?

Also is it possible only only select say a post on BASEBALL without checking the SPORT category but for it to count towards SPORT also without having to check it. For example, if I post 10 articles in just BASEBALL and 1 under SPORT only, it displays it as: SPORT (1) but when you click on it, it lists all 11 articles from BASEBALL and SPORT.

A little confusing I know but hopefully someone has the answer to both questions.

Thanks!!