Should thermal pads be connected to GND or not?
There is a whole page in the datasheet dedicated to the thermal pad, which specifies handling as in the document at http://www.ti.com/lit/an/slma002h/slma002h.pdf  

That document specifies "Check the respective product data sheet to verify which signal, power, or ground plane the device should be soldered to"

Given the absence of handling in the product data sheet, I would contact TI if this is important.  I would also choose not to design around that part if I couldn't get an authoritative answer, in writing, and move on to the next part that would suit my needs.

Update:  It looks like https://www.ti.com/lit/an/slma004b/slma004b.pdf now specifies that the thermal pads can be connected to the ground plane.  Still wishy washy enough to merit a check with TI