We most definitively need a way to link OSM data to external databases, and I really like the idea you propose. You have my vote!

OpenStreetMap is entirely user-driven data, and it makes sense to have user-driven ids to link with external databases as well.

Ce “gâteau qui vole” repose en fait dans ma main droite… Je votre assure que ce n’est pas retouché! (En tout cas pas cette partie de l’image)

Welcome! I hope you will enjoy contributing to the map as much as we all do!

OSM has a vibrant community, so if you need help, do not hesitate to ask! One good way could be to find local mappers near you and ask for help. There are also the mailing lists:

http://wiki.openstreetmap.org/wiki/Mailing_lists

Enjoy!