If the gross
weight is 10,000 pounds, you can drive it. Your run-of-the-mill Class D passenger car license is good for 26,000 pounds gross. (If you haven't renewed in several years, the card in your pocket might say 18,000 on the back, but the law changed.) If you drive it for hire, and it really has 48 seats, you will need a CDL with passenger endorsement.
The old half-ton Dodge van where I used to work was 6,000 pounds. If the 'suburban' (NYS for "station wagon") is only 10,000 lbs, it doesn't sound like it is a real bus. NYS law makes school districts transport students registered in schools outside the district in many cases, and so there are some station wagons and Chevy suburbans in School bus clothes that take one to eight students on runs to distant schools every day. It could be a real "suburban."
On the other hand, if it once was a real school bus, and weighs 10,000 pounds empty with the seats out, look at the data plate before you buy. If the gross weight is stamped 26,000 pounds or less, you are good to go. If it is 26,001 or more, you will need a Class B CDL until it is officially an RV. Then you will need an "R" endorsement on your Class D car license if you don't have a CDL B.
The license required in NYS is determined by the heaviest
1) the registered gross weight;
2)the chassis manufacturer's design gross weight; or
3) the actual loaded weight as seen on a scale.