He is correct, we swap them all to the hydrolic when changing them now, which is a better design, and after this is done you can change just the pulley in the future.
The cabin filter is the microfilter.
The idler pulley is the one that is held on with the alternator bolt that just holds the belt in place. (for proper contact path with alternator etc.)
As for prices, I can't help you... But I'm sure some people will be able to chime in.