Congratulations on opening your third branch. How exciting!
We're in a public library but since our library is understaffed, we had told the library director that we just needed space and would not put any burdens on their staff. So I can't speak to some of your questions.
We don't do any inventorying of seeds. It's a lot of time and we have a self-serve system that is not connected to the public library car system so tracking or cataloging isn't required. In the library, our seeds are mostly in jars so envelopes are provided and signage. Signage. Signage. Signage. I like putting labels inside of jars so folks can grab pre-printed labels with more detailed information, especially for rare and unusual plants. It's our regular envelop label that we normally stamp on, but it is printed out with the information on. 6 labels fit on 1 page. I have a good paper cutter so it goes pretty quickly. One goes on the outside of the jar and the rest go inside.
Peas and justice,