1) It's likely that the ban on Windows 8 has nothing to do with "power-saving". To me power-saving is just a buzzword in the title of the notice.
2) This notice is concerned with a specific round of bid. So it's not an administrative order, but rather a requirement list for the bidders. If I understand correctly this only applies to computers to be purchased during the bid. I'm not sure about how large the scale of the bid is, though; it may affect 1% of the government computer installations, or 99%. Either is possible without further information.
3) This notice doesn't say anything about Windows 7. What this means that bidders are allowed to provide computers pre-installed with Windows 7 and IMO this is pretty likely. Yes there are conspiracy advocates who would rather stick with Windows XP (I have never been able to understand their reasoning...), but I believe the computer vendors are more sensible. After all it's they who have to provide customer service.
4) This notice is also only concerned with the pre-installed OS. It's totally possible that the government officials may replace the OS with anything they like (which are, unfortunately, most likely pirate copies). I don't know about the central government, but it's common practice in local governments. The central government has very weak executive power when it comes to such detailed things. (Why bother enforcing such regulations after all?)