I know how to assign the same effect to different pads...but how can I assign different effects to different pads? So I can have delay on my hi hats, subsonic on my kicks, and c. canceler on snares?

You can only use 1 effect at a time on the 404... To do what you want to do you would need to put delay on your hi hats, resample that another pad with the delay on, which then frees up the effect enigine so you can apply subsonic to your snares etc...

Not to be an asshole, but you should really spend some time with the manual, as this and the other question you asked are clearly covered in the manual...