No need to wash or anything, I like to chop mine up ( just a rough chop not fine) and throw mine in au naturalle but I have a bottom draining fermenter so clogging isn't really an issue.
Others put them in a hop bag/ grain bag/ stockings or what not to prevent clogging the tap. This bag can also be weighted down with a couple stainless washers.
Throw them in the end of te boil to retain most of the flavour. I would advise on a bag or hop screen as I left 2-3L of wort in the kettle after mine blocked up. Not before 1 or 2 went into the plate chiller
I used 120g of fresh Cascade in a "pale ale" its more Indian than American or Australian.