Send 1to1 chat request to user hidden in GAL in Team

We just upgraded our Zimbra and Zextras installations to the latest releases (8.8.15 and 3.0.10, respectively) and, per other posts on this forum, disabled ZxChat.

We have some users hidden from the GAL so that users will use the distribution lists they're a part of instead, but those users also don't show up in Team. Is there a way to make it so that users can see them to send messages to them shy of not hiding them from the GAL?

Our license is a holdover from the last licensing scheme, do we need to make an additional purchase to have access to the advanced Team features, such as channels?

Our ZxChat history appears to be gone, I presume this is gone forever?

Is there any way to reproduce the buddy list functionality of ZxChat?