B/C: select a headstamp brand and use that in your load workup. Using the same brand will give you more consistent accuracy. For plinking only, it doesn't matter.

X: yes, using Lee collet dies eliminate the need for lube. Clean by dry/ wet tumble or by sonic. After dry, use collet to neck size. I love the collet dies because no need to lube.

Y: neck sizing can extend brass life. I still recommend inspection after each firing, trimming as needed (usually after 3-5 firings), and annealing. Annealing will prevent the necks from cracking. Some people anneal after each firing and some after 3-4. I anneal after 3-4.