The fiber side depends on your market segment. The highest quality fiber (clothing, rope) is derived from stalks harvested just after flowering initiates--i.e. after plants have stretched, but before flowers proliferate. Dual purpose crops (seed/oil + fiber) produce a low quality fiber that is only suitable for pulp/paper. Hempcrete is great; this is made from the woody core (high in silica, so it binds well with lime) and can be derived as a secondary product from any cannabis crop. As you said though, the equipment is spendy and cannabis stalks have a tendency to quickly destroy any implement they come in contact with...a great testament to the strength and durability of the plant!
We donate our stalks to nearby hempcrete builders at the end of the season. We grow sinsemilla, just like other cannabis farmers, solely for CO2 extraction. Our seed production sites are for breeding purposes; we produce these for ourselves and other growers to ensure a steady supply of affordable, CBD -rich, "industrial hemp qualified" seed.