Possible project, how simple or difficult?

I am considering using OSM for a project for my home town city council. They want to present their parks and squares in their webpages in some kind of map presentation. The areas should be highlighted when hovering over them, and clickable to more detailed information about what kind of infrastructure is available–like water, electricity and such. This is information they would like to add to the map, but which should not necessarily be freely available on OSM. However, this might not be a problem.
In the end, the park/square objects should be clickable and linked to their own database allowing people to book them for events and such.

The booking part is of course completely separate, but I would like to get some views on what obstacles we might encounter if we try solving this through OSM. :confused:

Whatever you add to the OSM database has to be freely available. Check out the odbl.

How the data is presented to the user is beyond the scope of OSM as such. You will have to write your own application for that.

Seems like openlayers allows adding elements to web layers “above” OSM. Maybe this could be my best approach?

Would the shapes of the parks/squares come from OSM or the council?

From the city council, manually drawn. But the borders of the parks and squares would of course in a number of instances partially follow the edges of areas already existing in OSM.

Allright, so I agree that an overlay of interactive elements (e.g. markers, lines, areas) on top of a map layer would be the best solution. The popular Javascript libraries such as OpenLayers and Leaflet support this, and it simplifies the legal situation if the two datasets remain separate.