The film's focus is entirely on Dorrington and his struggles to complete his experience of the past and to move on. Herzog only digresses in order to give Dorrington some breathing room and time to be with his thoughts.
Initially, yes, but that was not the case after the scene shifted to Guyana. There were sequences – involving Yhap’s chickens, the locals the filmmaker tried to impress, etc. – that were merely fill-ins. If Herzog allowed his protagonist to have some breathing room, then there wouldn't have been so many shots that lingered on his face, waiting for him to react to something. Those didn't do much for me, and, I think, that was also the case for Herzog. But, overall, I still liked the doc.

As far as I know, the original soundtrack doesn’t exist at this point. However, I was able to locate the soundtrack credits. Winter & Winter label holds the rights, and after searching their website, it looks like 4 of the 6 tracks came from the album listed at the bottom of this page. An e-mail address (info@winterandwinter.com) is available for more info.