Regarding Google Maps, it does work but force closes whenever I attempt to open the settings (I'm sure because it can't find the account). Hence, I can't sync my places or use latitude.
Paid apps through Play are possible with an appropriate SIM card (UK in my case) and connecting over WiFi. I have bought apps in China from the UK market in this way on my old phone. I don't think I used VPN at the time (which now seems no longer to work over WiFi so Youtube is definitely out!).
I'm not too fussed about buying more but really want my old ones to work (especially Hanping Chinese!)