You probably want to read the general info about cages and cage size. Also read about social life on
Index of /. Most store bought cages are not very good for piggies.
Pigs have bad depth perception, so they can't judge heights very well. If you have any ramps or open edges, the sides should be walled/blocked so that your piggie does not fall off. They don't do well with falling or climbing. Their legs are too short. Slick ramps are also bad. They need decent traction or they just slip around and slide off.
If it is like one of those ferret cages, wth levels and ramps on the inside that have all open edges
At 2 1/2 months, he should be fine for general exercise. They are born practically ready to go. Just made sure there is nothing bad around that he may try to eat or chew on.
If the ramp leads out of the cage, he will do his business outside his cage.
They can be house trained for pee to some degree, but not as much for poop.