Question on Group, Team Members, and access/visibility to data

I have several groups setup so users in different groups cannot view their data.  These users in the same group's role has been set with (Has Access?) and (Can Create?) for the Record Type Access.  They CANNOT Read all Records.  With this configured, I thought these people in the same group can view other peoples data considering they are in the same group? 

Is this restricted because Read All Records is disabled?

Is adding members into Account Team/Lead Team the only way for people in the same group to view their data? This will not work as there are too much data and has to be done manually adding people into the team members, unless if there is a faster way of adding users into the team members...