It is one unit, which makes it easier on you to replace.

Its not difficult at all. The hardest obstacle will be removing the stupid rotor retaining screws, which I recommend you drill out, as theyre not needed anyway and only get in the way in the future.

Cake install...try and pick one up at a junkyard, just make sure its in good shape (feel the bearing, make sure its totally smooth...there is a feel to it). The part is pricey from Acura...a generic one will run you about $100...and one from a wrecked car...maybe $15.