I am new at this as well. I had followed the directions on setting up the die and sized some .223 brass. Then as I read more I became concerned about shoulder set back, and how the shoulder of the case is what stops the case's forward movement into the chamber which in turn defines the space between the bolt face and the head.
So I ordered a Dillon case gauge and dropped them in. Sure enough the case head was well below the gauge. Oops. But at least I know. I use the length feature as well, I run my finger nail across it to feel. I trimmed all of my cases, some didn't have any material trim off, some did, but I use the case gauge all the time. I have it setting there and when I primed the cases I dropped them in again, and guess what, I found one case out of almost 100 that hadn't been resized. Go figure. So, I use it all the time. I just used it again when I charged and seated 15 rounds to work up my first loads.
Case lube lasts so long that I am not sure if I would make my own. I actually dread the idea of a stuck case. I grew up on a farm and I have a knack for breaking machinery, too much torque and snap off bolt heads and then out come the drill and easy-out and my Dad scowling...
I seated the primers with a hand tool. Out of the entire process the primers get my respect and attention immediately.