You can make use of jQuery in your case.
jquery.min is that,
jquery.min is minified jQuery. Basically minification compresses code. Minificated code is hard to read but it's excellent solution when you put application in production. It'll save you bandwidth, your site will be faster and you'll get better site ratings (on sites like Google PageInsight).
For development, you can go with
jquery, because it can make you easier to debug application. When you're ready to put app in production, it's recommended to change it to 'jquery.min`.
About jQuery communites, you can even try asking here. The biggest community, where you'll find all answers is definitely StackOverflow. It has answers for almost all question you have. For fastest answer this is probably best place. There is jQuery Forums and jQuery IRC channel, but I'm not sure how fast you'll get response there.