Android App with data overlay

Hey guys,

I’d like to implement a mobile OSM Android app and overlay it with nodes/objects and polygons or clouds (like heatmaps or heightmaps) derived from dynamically generated and partially user-specific data.
This visualized data should come from my own database, delivered by a webservice, presented to the user for his current location.

Since there are tons of stuff like frameworks, databases and tools, I’m a bit confused where to start.
What Application Server, Webservice, Database (PostGIS?), GIS exchange format to use? Is it better to render the data overlay at the client device or render overlay tiles on server side… I guess I prefer the first approach since less data has to be transmitted and most devices are fast enough nowadays.

Yet, I successfully implemented a small android app with mapforge (and a local mapfile on sdcard), continiously updating and showing the users current location.

Do you have any suggestions or best practices for me, where to start and which technologies to use in this project?