Are there any plugins, scripts, extensions etc that one could install that automatically encrypts stuff that is over 5 months old? Occasionally I need stuff from back then when I would need to search for it -- which I guess would be problematic? Is there a solution to protecting this stuff w/o deleting it from the server?

You can set your phone to GSM only.. (which lots of people do as it increases battery life and generally gives a better call quality) .. Or just put a few phones doing data connections on UMTS at the time of the demo.. It will take up most of the connection (used to be max of 7 per cell).. then everyone else will be diverted to GSM

I have it on good authority (I've worked at my fair share of cell phone operators globally) that all of the Major networks around the world will be going to LTE.. If they are on CDMA now (like Verizon) they will go straight to LET, if they are on GSM / wCDMA / UMTS they will go to LTE next..

Its not a question of if but when..