In answer to part of your question, there are probably no other reasons for large-scale cultivation of hops in the 8th century other than for brewing. While hops were used in medicine, the major national herbals of Anglo-Saxon England don't mention them. That we have strong references in early 8th century England (see "Anglo-Saxon Food and Drink" by Ann Hagen) to comparatively large-scale cultivation of hops strongly suggests they were used in brewing.
Hops are used in medicine as well, but the amounts used there are very small in comparison to those used for brewing, and the two major Anglo-Saxon national herbals, Bald's Leechbook and The Lacnunga don't mention them (I think the Old English Herbarium does, but it is a translation into Old English of a continental Latin work). Keep in mind most of my work with these has been in translation (Pollington's) and translating plants from the descriptions often poses interesting issues. I could probably find standarized editions in Old English if needed however.
One of the interesting connections here is that two of the most important early brewing herbs, hops and henbane, both had strong connections to female medical concerns (this is also interesting because historically brewing was women's work, hence the obsolete term "alewife" not referring to a fish--- the woman's place in keeping a tavern was privileged but brewing was sort of like cooking, something every woman was supposed to know). Hops to heavy periods, and henbane was used to address pain in childbirth. Both of these may contribute to Bald's warning that pregnant women may drink ale safely but not beer, for beer would cause a risk of miscarriage.
In general for hops to be grown to an extent noteworthy, one is almost certainly talking about brewing, whether grains or honey, and whether alone or with other herbs.