My Moog joints for my F150 have the "relief valve" on them. As said, the instructions (yes, I read them) say to point them inboard away from the rotor.
As for completely getting all the old grease out each time, no, you should do it till clean grease starts coming out the relief (usually 4-5 squirts every 5000 miles does it for me, the first 2 are just priming everything up, the last 3 are actually pushing old grease out).