OpenstreetMap how to validate post addresses

I am working on a project where I should develop an application to validate post addresses in Germany, Switzerland and Austria. For that I need to set up a address database with all information. But I don't know where i can get the data. I googled for a long time but I didn't find an answer for my problem. I have 2 questions:

1. can I work with the rest service of nominatim in a productive environment? the application will process approximately over then 300000 request a day.
2. can I import an openstreetmap file (*.osm) in a DB (MySql) and work with that? ist there all the informations i need to validate addresses. such as streetname exists? housenumber exists? fit street to housenumber and town?

thans in advance

Achraf

1. Yes, you can use Nominatim in a productive environment. However not OSM's public instance (take a look at the usage policy for the reasons). Just install your own Nominatim instance or use one of the other alternatives.
2. That depends on the exact information you need. Some adress information are implicitly contained (usually address, house number), some others need to be calculated first (often the city, municipality, state, post codes etc.) because they are often not attached to the address elements directly but to administrative boundary relations instead. Nominatim does all of these processing for you.

Also take a look at other OSM search engines. And remember that OSM doesn't contain every possible address.