Can I create a individual budget for every single category and sub category in the categories list? Which is the procedure?

A budget can be created for a calendar year and in that budget you can assign income and expenses to all the categories. This means that if you want a budget for individual categories you can create one and assign an amount only for that category. You can find more about budgets in the manual at http://kmymoney2.sourceforge.net/kde4/online-manual/details.budgets.html.

Thanks a lot for the quick answer!