i plan on wiring 5 or 6 outlets indoors in a chain, i will be using 12-2 NM wire with a metal 4" box. i need clarification on a few points before i proceed please.

1)for a single duplex outlet in a 4" box - is it better to feed the outlet from the top set of screws and continue out to the next from the bottom set OR pigtail 3 wires together ("in" from supply/"out" to next outlet/and outlet supply)

2)for 2 duplex outlets in a 4" box - is it correct to
pigtail 3 wires together - "in" from supply/"out" to next outlet/and "first" outlet supply and than supply the second outlet from the bottom set of screws on the first outlet?

3)for grounding
in each box will i be correct if i take the two ends of the bare copper ground and pigtail it to a green ground wire and then attach it to the grounding screw of the outlet, or for 2 duplex outlets in a 4" box make the same grounding pigtail with 4 wires

AND

should the metal box be grounded as well, and if so whats the easiest way to do it assuming you have 2 outlets in the box

thanks