Greasing question.

Any part should be "unloaded" to really get thoroughly greased...
for examples, as mentioned, taking weight off the king pins. I like to jack at the frame rail, when the weight comes of the springs grease the shackles then when the wheel comes off the ground check for slop in your wheel bearing and kingpin then grease the kingpin...
Block your wheels, release the brakes then check your brakes, adjust and grease your slacks and S cams.

Not absolutely necessary to jack it up every time you grease but try to do it on some regularity!! It will save aggravation and wear...