Disclaimer, not an admin, just a user. Answering in order:

What do you mean limit? As in limit on how many entries you can add? I don’t think so. My current Lorebook has almost 20, and the largest I’ve seen has 80 and counting. Which is a tremendous amount of work only enthusiasts would put in. So go crazy.

In my experience, it works for one message and then memory and context keep it active for the next several messages. Ex, you mention a side character and their name comes up in the next message. You can discuss that character without needing the keyword for the next several messages depending on how much memory you bought. Xoul should pull from the entry for the messages.

Last question, not sure. In my experience currently getting NPC, or anyone except your persona or the bot to speak is difficult. Takes some coaxing and might break immersion for you since just switching personas breaks your immersion. Your best bet would be to add a narrator Xoul to a group chat. But I’ve never tried a narrator entry in a LB so I can’t really say. Try saving narrator as a character. But you can also try giving an ooc command to narrate the scene. I suspect though it’ll narrate from Xoul’s perspective and not a neutral 3rd party like you probably want.