Question on 1997 Pontiac Grand Prix GTP Supercharged

I went and looked at a 1997 Pontiac Grand Prix today. It has the 3.8L V6 supercharged other options include.

Leather Interior
Heated driver seat
ABS
4 wheel disc breaks
tires are only 1 year old. Good tread left
power seats
Spoiler
AC. Good condition


basically it has everything.

The question I have is that the factory radio has been removed and a nice after market radio was put in. However this car has the steering wheel controls for the factory radio. My 2000 Monte Carlo factory radio has settings to reset all the onboard message center stuff that comes up.

I was wondering if it was the same for the 1997 Pontiac Grand prix.

I test drove the car today and it runs great. Really fast everything seems to be working properly but all the idiot lights are on like

service engine soon
Seat belt ect. Ect.

I was wondering if the removal of the factory radio would have caused this and if it should be a major concern. I am thinking about buying this car within the next couple days and would like to have some constructive criticism.