Create members-only map site with customized icons and selectable layers

Hello to everyone. First of all, Im totally new to the map world, so forgive me if my question is too dumb and / or has been answered somewhere else that I haven't been able to find. I'm helping on a project for a map on "quality of water" that should have the following features:

• Collaborative but only for members of the network
• Customized icons (to have a rank from, say, 5 to 1 on quality of water)
• Creation of different layers of content (quality of water, quantity of water, rural / urban, etc) to choose from.
• Possibility to change the language in certain features

I've been making reaserch for two days, and I've found about several tools, like mapnik, openlayer, leaflet, Ushahidi, but I'm wondering if anyone can suggest at least a draft of the workflow that I should follow. I've found too many options, add ons, libraries, and I can't seem to find a beginning point. If anyone can throw some light on this lost sheep, I'll be very very very very grateful. Thanks a lot!