This speaker wants everyone to join in on the fun. Anybody and everybody can and should be a pioneer. In fact, we are all pioneers. Go figure. In Whitman's world, everybody is connected to everyone else—and the entire cosmos—through this pioneering spirit. He blurs the lines between people and things to show us that those lines aren't even all that useful in the first place.
Line 3: This rhetorical question, right at the start of the poem, seems to include us, the readers, in the pioneers he's writing about. By speaking to us directly and including us among the group he's writing about, he blurs our notion of separation between ourselves and the text. See? We're all connected—even to the books we read. Fancy that.
Lines 65-67: The anaphora in this line (all the phrases beginning with "all the") adds to the way that our speaker is putting all these people on the same level. By introducing them all with the same words, in the same way, it lends a sense of equality, which makes the distinction between righteous and wicked seem a whole lot less significant. Maybe there's not even a distinction at all?
Lines 69-71: Our speaker not only distinguishes his soul and body from himself, but he also personifies them, so that they can accompany him on his way across the shores of the world (a metaphor, by the way). By doing this, our speaker tests our notions of self-identity. Are you a single, unified self? Or a body and a soul? Or a self and a body and a soul? Are you connected to stuff around you or separate from it? And what do those distinctions mean? These are all questions lurking behind that image, and they're pretty hefty.