Yes the parasite cleanse is a good thing to do first, although I never did it. The parasite cleanse is not going to have any big effect, it is done to prepare for the liver cleanse so there won't be any pain involved. However, all I did was change my diet and cleanse my colon, and the Liver Flushes have been going fine.
I do Dr. Clarks Liver Flush which is on this site (epsom salt/olive oil). I try to follow the directions as closely as I can (which aren't too complicated), but I do push all the steps a couple hours back so I can go to bed at 12:00 instead of 10:00, and I still get great results. As for any down time the flush causes, the only time I'm "out of commission" is a few hours the morning after the flush when the diarrhea ensues. I never feel any sicknes or discomfort (maybe a little nausea here and there while drinking the nasty potions)and afterwards you'll feel revived. I also have had bad allergies, and in the two months since I started flushing, nothing! It's truly amazing.
As for P&B shakes, I never tried it, so I have no advice. They never really seemed neccessary to me. Good luck!