Will this MOSFET be suitable for driving a 12V 1-2A Load from an Arduino?
Forget Vt. What you should look at is Rds(on) at 5V drive which is 0.02 ohm maximum (will increase with heating, but not more than 50%). At 2A the heating will be no more than 120mW  so you won't be needing a heat sink for static switching (you can verify my latter claim from the thermal characteristics). The 0.02 ohm is a 100% tested guarantee by the manufacturer, not a "typical" characteristic, which may or may not be accurate for any given device. 



If your PWM frequency is high, there may be significant heating from the slow switching due to not having a high current gate driver but at a few hundred Hz it will almost surely be fine.