converting from MTB to hybrid, what should I consider
First, term hybrid is sometimes used for quite different bicycles (rigid or suspended front fork, caliper or canti rim brakes)

I think there are no big difference in maintenance. Maybe to check more often your wheels and spokes since they might be more stressed.

As for riding style, you have to go more easy on curbs, and all kind of holes on the road. Your brakes will be less effective, especially in the rain or snow.