It's very easy to change the pads and rotors on the 190E. Once you remove the calipers, the rotors are held on by one hex bolt. Remove that bolt and they will come of. You shouldn't need to re-pack the bearings. No, you don't need to do anything with the ABS system.

The brake pads are very easy as well. On the front calipers you simply remove one bolt, flip up the rotor, replace the pads, and replace the bolt with the new one that comes with the pads. On the rear calipers, you simply have to tap out the two retaining pins, replace the pads, and tap the pins back into place.

The Haynes manual for the 190E does a very good job of explaining the procedure.