Please follow this post on how to install the template kit on your WordPress site.

The licence is under GPL. Yes, you can use this template kit for your client. If you give donation,  mentions or backlinks to my site, it would be appreciated.

Sure, you can shoot me an email or using contact form. I also provide profesional service for installing or design a website kit.

Of course, all the themes, plugins, and template kits will be maintained.