Regarding documentation, do a search (entire site) on NI's site with either "+out +port" or "+parallel +port" target and you'll have lots of examples and documentation.
Regarding boolean operators with u8, they are used to set or clear some lines, based on previous values (OR is to used to enable, AND to disable - for example, you want to enable the third line (bit) without affecting the others ... thus, read value - perform OR 4 (which is 00000100) - write value).
Hope this helps