Running an android system without any google apps or services installed is pretty doable actually
The only gotcha: A lot of apps require the google maps framework (not the app) which can be installed fairly easily. To add on this, copying the jar file is not even needed. Doing this you can still install apps that require the google maps framework without actually installing the framework. The xml file is a simple mapping of the service name to the jar file. Be advised though: apps will crash once they actually try to use the framework.
Virtualbox seems to have problems with keeping the clock of the virtual pc consistent - so time drift is very likely to happen. Usinig ntp on the guest does not counteract this since ntp will bail if the time difference is to big. Using
ntpd -gq forces ntp to get a complete new clock reading and updating the system clock (The NTP service has to be stopped for this to work)
NTP does not update your clock if it is up - it syncs your clock with an ntp server by prolonging or shortening the time of a second over a particular period of time. This way time is still linear for all other applications and does not suddenly jump from one time to another.