Will I have issues using a Bold 9900 on AT&T in 2016?

I'm looking at moving from an iPhone 6S to a Bold 9900 (I know). I'm on AT&T. I used a Curve way back when.

Aside from needing a SIM adapter, are there any other issues that might complicate using a Bold 9900 on the ATT network in 2016? Or do I just pop in the SIM and get started?

Specifically:

-Will the Bold be able to use the data plan I currently have for my iPhone?
-Will I have any issues receiving Gmail messages on the Bold? Will emails be pushed?
-Anything else I should consider here?

Thanks...

Hi there,

You'll need to get a BIS plan. The data plan for iPhones and other generic smartphone data plans won't work.