In most of the countries you wrote there are very good long distance cycle paths (for example, we haven't them in Italy, except for Trentino Alto Adige
), so I'd suggest to follow them.
For my tour across Europe I found the cycle paths using two of the links which has been told in previous posts: Germany Tourism, and Esterbauer. Both are great resources. Esterbauer guides are wonderful!!
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About free camping I know nothing actually, but the campings we found in the last summer tour were not so bad.