Our themes are not encrypted, so you are free to customize it as much as you like, and in doing so, we recommend the use of a
child theme in order to retain your modifications in the process of an update. Technically you can do whatever you would like, given the relevant level of coding knowledge to implement such changes (which it sounds like you have covered ;) )
Our licences allow you to develop websites for clients and sell them, but we do not have resellers for our themes. If you did develop a child theme which you think could offer features/layout that others would be interested in, you may also like to look at the
AppThemes Marketplace as a place to potentially offer it to others. More info
here. Thanks.