Get the current group ID

  //GET THIS GROUPS ID
  $guid = bp_get_current_group_id();
  if (!is_numeric($guid))
    die('Unable to get group ID');

Get groups user is a member of

Note – in our tests using a different users user_id instead of bp_displayed_user_id() returned zero results – appears to be a buddypress bug

  $GroupIds = groups_get_user_groups(bp_loggedin_user_id());
  $GroupIds = $GroupIds['groups'];
  foreach ($GroupIds as $GroupId)
  {
  }

Does group exist?

  if (bp_get_group($GroupId) === False)   //Returns the Group object if found, false otherwise.
  {
    return('Invalid group');
  }

Is user group admin?

  if (groups_is_user_admin(bp_loggedin_user_id(), $GroupId) === False)    //(Returns False or ID of the membership if the user is admin)
  {
    return('Invalid user');
  }

Is user a member of group?

  if (groups_is_user_member( bp_loggedin_user_id(), $GroupId ) === False)    //Returns False or ID
    return("Not authorised");

  if (groups_is_user_member( bp_loggedin_user_id(), $GroupId ) !== False)    //Returns False or ID
    return("User is a member");

Get group name

  $GroupObject = groups_get_group($GroupId);
  $GroupName = $GroupObject->name;

Get group slug

  $GroupObject = groups_get_group($GroupId);
  $GroupSlug = $GroupObject->slug;

Get Group Admins

  $GroupAdmins = groups_get_group_admins($GroupId);
  //print_r($GroupAdmins);
  $GroupAdminsUserIds = array();
  foreach ($GroupAdmins as $NextGroupAdmin)
  {
    $GroupAdminsUserIds[] = $NextGroupAdmin->user_id;
  }
  if (empty($GroupAdminsUserIds))
    return("Could not find group admin");

Get Group Members

  //------ GET GROUP MEMBERS -----
  $GroupMembers = groups_get_group_members(array('group_id' => $GroupId, 'exclude_admins_mods' => false));
  //print_r($GroupMembers);
  $GroupMembersUserIds = array();
  foreach ($GroupMembers['members'] as $GroupMember)
    $GroupMembersUserIds[] = $GroupMember->ID;