A1. No. but you can be quick and copy the contents of "C:\$Windows.~BT" before system reboot and installation begin. then you can make iso of them, and No, they are not for your system only. A2. Yes. activation is reserved, WMC edition will give you windows 8.1 pro wmc edition upgrade. VL (kms) activated system do'nt get store upgrade. If you are using non-activated retail edition, you still get store upgrade. A3. correct if you have genuine Windows 8 retail/oem key.
A2: Store update doesn't appear if you don't have a retail activated copy (legal, no VL or KMS allowed) A3: Yes A4: I don't know A5: I don't know About office, i think that no kms activation is working under windows 8.1 (Offce 2010 and 2013). Office 2003 and 2007 don't know if works