Thinking about switching from Android

[plsrespond8]

I'm looking at the Ativ S, but I have a few questions.

If I buy the unlocked version on ebay, will it work on AT&T here in the USA without any issues (3g and MMS, etc)?

Will the ativ S get the windows phone 8.1 update that should be coming out?

 

[lewis0663]

It should be working properly without any issue.
We don't have any clue about the coming updates. Why don't you think about the Lumia devices?