How to acheive specific Organic Group permissions?

Hi,

I am wondering if it is possible to create the following permissions in organic groups (Open Atrium) Drupal 6.

1. Any user can make themselves a Manager role
2. Only Managers can create new groups
3. Managers can only manage groups they have created AND/OR groups they have been invited to AND given the permissions by an existing group manager to be a manager of that group as well.

I have come across this module http://drupal.org/project/og_perm but not sure if it does what I am talking about, and also it does not describe an upgrade path to Drupal 7 just that its function is already in Drupal 7.

Open Atrium has obviously not yet upgraded to D7... but what ever I do here would need a path to upgrade.

Thanks very much in advance : )