To determine how many people can be in there, just use the same rule for passengers couches (2 per DT). So a 4DT library could hold approximately 8 people, but more than likely its really just 5-6 so you have some extra room. Or be more generous and say 1 per DT. Viola.
As for finding stuff... we have effecient search mechanisms today. It's easy to find information. It's hard to find relevant information for what you want. Smarter algorithms will surely help, but you are also going to massively increase the amount of information to be searched.
Here we have 7 contintents, about 130 or so countries, hundreds more subcultures and languages. Now multiple that by thousands of worlds, a much longer history, additional races, etc. I think they'll be in the same boat we are - but they'll be able to sort stuff faster, but still have an issue with relevance. Some things change, some things stay the same.
As for finding stuff... we have effecient search mechanisms today. It's easy to find information. It's hard to find relevant information for what you want. Smarter algorithms will surely help, but you are also going to massively increase the amount of information to be searched.
Here we have 7 contintents, about 130 or so countries, hundreds more subcultures and languages. Now multiple that by thousands of worlds, a much longer history, additional races, etc. I think they'll be in the same boat we are - but they'll be able to sort stuff faster, but still have an issue with relevance. Some things change, some things stay the same.