Hi,
I bought a Google Nexus 10 tablet some time ago. It's working perfectly with numerous routers and mobile phones (Android) excluding Windows Phone. I'm speaking about using my Lumia 820 as a Wi-Fi hotspot. Lumia 620 and 625 are the other devices I have tested. Internet sharing problem...
I'm not sure if this is new to WP 8.1 Update 1 but there's a new way to save a phone number. Go to calls (or whatever in english) and then keyboard. Now type a number and then save on the right corner. :)