Which tools to use for Responsive and Custom web site?

I'm not up to date with web software development and I wish to start a new project, so I have a few questions to start in the right direction.

I'm currently looking to build a new kind of application, something responsive (like Upworks or IdeaDrop by example).

This web site will have content, blog, mailing list, etc etc... but also some specific modules and a specific database that has to be build.

So, my questions are: - which language to use ? PHP ? - which framework ? (Auth, DB Connection, etc etc...) - which database ? MySQL ? - Is it a good idea to use Wordpress (by example !!) to create the content, blog, handle the users etc ... then create specific modules ? - Is there some tools to prototype the pages (Like Macaw etc ...)

Any suggestion is welcome :-)

Thanks