Like jQuery itself, all plugins are open-source, dual-licensed under MIT and GPL. Feel free to choose whichever license you prefer and use them whereever you’d like.
Plugins are developed and enhanced on a request basis. If you feel that something is missing or not working as expected, let me know via comments on this site or email, and I’ll see what can be done about it. Odds to get help are better, say, about 1200%, when you can provide a simple test or demo page.
If you’d like to use one of the plugins but haven’t worked with jQuery itself yet, I recommend starting with the Getting Started Guide. It provides a quick overview – from the very basics to using and writing plugins. If you are already experienced with jQuery and need to look up certain methods, the API browser may be helpful.
If you enjoy using one of the plugins and feel generous, I’d welcome a donation: via my amazon wishlist or paypal: