A couple things - you can 'load library' from any model file (at any location), which doesn't have to be a specific library OSM in the library directory. So if you want to create a master library of space types, schedules, etc that you've manually created or edited in previous models, you can easily load that model as a 'library' to copy the content into your master without having to duplicate the manual effort.

There's not currently a way to pull OSM data from the BCL Components list like there is with measures, at least not from within the application. You would likely need to download the OSMs (or IDFs, and import into an OSM), and then load them as a 'library'.

Regarding the DOE reference data, this measure will purge your model of orphaned space types and resources.

Git rid of all the schedules and constructions you don't need! This is a pain but if you do it once and create a template, then all of the projects want have all of that junk in them. We also added more schedules we use all of the time and made a few things that were annoying to build such as DHW loops. I think the easiest way to use them is just to open the .osm at the start of the project, save as, and then start building the model.

The answers above are correct, but I wanted to mention an alternative method under development. This repo contains OS measure development work to reproduce the DOE reference buildings. The workflow pulls data definitions from a spreadsheet to automate generation of the model. The approach (specifically the spreadsheet content) can be extended to create other models, e.g. baselines compliant with other standards. The resulting measure set will be formally released around September, but you can inspect the code in its current state in the repo.