So yeah, after a few months I have more info for you about this project!
Check out the new documents and pictures.
The tuner we're using has two chips - TEA6810V and TEA6825T. It packs AM, stereo FM, RDS and is controlled via I2C. The board itself (schematic and board files are somewhere around this page) has a TDA7313N signal processor, also controlled via I2C. The board has a 2x35W amp, a L5956 supplying +8V5, +5V and +3V3 for the other chips. The address of each chip is 7-bit, watch out for that. It can be powered by an AC transformator that outputs max 12V and is able to supply at least 70W or a max 14V min 14A DC supply.
Please leave your questions, ideas and opinions in the comments, I appreciate it. Next update will probably a software update about the Python library and implementation of on-demand internet music services, so follow if you are interested in this project!