Point #1---damn it. I haven't read much Sandburg, but something did sound very familiar. Looking up his poem, it's different enough in tone and intent to be okay with me. I'll just chalk it up as another contribution to the "air with feet" motif--not as grievous a crime as adding another "fire as desire" poem to the pile ;) For the curious, compare the above with Sandburg here:
http://eir.library.utoronto.ca/rpo/display/poem1791.html
Point #2 well taken--I made an edit to correct that.