Did your car have airbags in the original seats? If you hooked up the airbags in the new seats, thats why the airbag light is lit.
As for the seatbelt light im not sure. Sorry I cant be much help...
My car: 2014 Focus ST3
My Moms: 2009 Sangria SES Sedan
My Bro's: 04 Silver ZX5 SVT EAP
Team Duratec # 136