Is it possible to restrict visibility of work items to certain teams

We need to restrict work items on team basis. For instance,  when two work items are assigned to two different teams, only those in the team should be able to access the respective work items. The flow will be  -

a) User selects a group name while creating a work item.

b) Work item is assigned to team. None other than the creator and the team will have access to the created item.

c) Only the users in the assigned team (not even the creator) will be able to update the 'Owned By' and 'Priority' attributes.

Our asks are -

1) How to implement the above flow?

2) While using 'Restricted Access', the drop down displays the project areas. How to display the team areas rather than project areas?

3) While 'Restricted Access' was added in one presentation, all presentations were automatically updated with this (Restricted Access). How to restrict this to particular items only?

4) How to exclude some of the project areas from appearing in 'Restricted Access' drop down? We don't want all to appear here.