Regarding #1, It looks like this can be implemented within the current functionality as follows:

When the client is viewing the chat channel, have the client write a user entity saying, in this channel I have read messages up to (the date of the most recent message they have seen). Next, when the app loads the next time, call “getRecentChatMessages” and count up the messages since (the date of the most recent message they have seen). This will give you your count to show for that channel.

Limitations:
The chat queue for a channel has a limit of 250.
Messages have max days and max history (settable by the developer) so if the players been away a long time, some of those messages wont be around to be counted up.
Go to Messaging Chat to view the settings for these.

Regarding #3, The app can store the GroupOwner information in the GroupSummary data which comes back with ListGroups anyway. For existing groups, on login, have the client call GetMyGroups and UpdateGroupSummaryData for any owned groups. The GroupSummary data area is super useful, you could also put say, a group vibe “Casual”, faction alignment or other group descriptor as well.

Regarding #5 we discussed this idea. The devs emphasized that the description text block can be stored in the GroupSummary or GroupEntities areas. This keeps the system as broadly compatible and efficient as possible for all customers.