Responsive CMS based Website required for our heritage-focussed community group

Website Spec
I require a fun dynamic website for our heritage-focussed community group. Preferably built on Joomla, (as we have knowledge of maintaining content in Joomla) but would also consider another CMS if deemed appropriate. Would like as many of these features as possible within our budget:

Responsive Site (i.e. optimised for tablet, mobile, desktop etc)

Home Page
Interactive calendar of events. click on event dates, to show details (perhaps in a popup window) , Ability to accept review comments of events for registered users
Small Photo Gallery
Current Campaigns/ Debates / Voting - control access. registered users only versus open for all
Newsletter / Latest News
Song of the week (users vote for song and we allow streaming of a song
RSS feeds
Links to a variety of internet radio stations
Members Area - Password controlled with access to protected pages and moderated chat group
Google plus / Twitter / Facebook links
About US
Text about our history etc

Workshops
This page will show the various workshops that we offer - Show sample of workshop material i.e. images and sample content, photos of workshops, show reviews that we’ve received from schools that have used .

More Photos
Photo Gallery

Become a member
Membership signup (option to pay via paypal)
Enquiry Form

Friends
Friends of our community group / Directory of businesses

Other / General
Basic editing to tidy up logo
SEO friendly
Site should be light and quick to load. Modern, Fun with clear clean design
On the home page in particular, we’d like the ability to expand articles to show more, without navigating to a new page if possible.

we’d like the ability to be able to insert small images in line with the text in the articles. A bit like a magazine.

We require a ‘staging’ site to be able test changes before copying / moving to live

Hosting
We already have web space from Justhost.com