как долго поддерживаются релизы debian?
Если ознакомиться с en.wikipedia.org/wiki/Debian#Release_history то ответ можете получить в графе «Supported until»
www.debian.org/security/faq#lifespan
Q: How long will security updates be provided?

A: The security team tries to support a stable distribution for about one year after the next stable distribution has been released, except when another stable distribution is released within this year. It is not possible to support three distributions; supporting two simultaneously is already difficult enough. 

Перевод требуется?

Репозитории для старых релизов доступны тут: archive.debian.org/debian/dists/