OpenACS might not need UTF-8, but your application might, once you want to entry arbitrary characters over the web interface. The encoding seems to be a well known openbsd problem. [1] recommends "initdb -D /var/postgresql/data/ --no-locale -E UTF8".
The sections of the manual are not intended for sequential reading, and yes, much of these comes from a mindset, that every openacs admin has to install everything "by hand". If one looks at [2], it is certainly true that chap 11 must be understood before chap 9. Most of the install infos are completely out of date. maybe we can make some cleanup for OpenACS 5.9.1. Any help to improve the documentation is certainly welcome. If one is using openacs over many years, one gets blind for such issues.
The following papers [3,4] might help to understand the conceptual background and the file-system structure better...
all the best
-g
[1] http://comments.gmane.org/gmane.os.openbsd.misc/219443
[2] https://openacs.org/doc/acs-core-docs
[3] https://openacs.org/storage/download/OpenACS_Tutorial.pdf?file_id=2855307
[4] https://openacs.org/file/483757/OpenACS-full-paper.1.5.pdf.pdf