These arcs do not affect the main plot. Many fans recommend skipping them on a first watch and returning to them later if you want more content.
Bleach episode 5, "," is part of the initial Substitute Soul Reaper arc and focuses on Ichigo and Rukia dealing with the Hollow known as Shrieker.
Widely considered the series' peak. Watch every episode here, though some guides suggest skipping episode 33 and 50 as they are standalone filler.