While i let the rtv set a bit longer i have some Q's.

Can someone inform me how our pcv system works?
If the oil cap is getting sucked in it means just the front pcv is plugged? How will i know if the rear is plugged? If i HAVE to i will just slap a breather on. If i do this will i hurt anything? Will it just vent the front? Then i wont know if the rear is working?
Sorry for the rant. Had this apart 5x in a few days.