Hello, 

As per my understanding, you want the sales team have multiple hierachy and the proper access right such as sales team leader can see only his/her team's document, however odoo standard will have several limtation: 

1. As per the access righ you can only have 2 option: see own documents or see all documents, that mean see all document of all sales teams not helping when you want to have access right for one team only.

2. Odoo do not have the sales team hierachy feature and cannot give access right by sales team or parent sales team. 

Therefore we develope a module to fix that, you can check out this: 

 https://apps.odoo.com/apps/modules/16.0/s_multilevel_salesteam_operation/

User manual in Vietnamese here: 

https://bisfast.com/docs/crm-1#hoat-dong-nhom-ban-hang-da-cap-124-0

Hi there!

Actually, this "Team Leader" field doesn't affect access rights.
It is there to display who is responsible of the sales team.

If you want your salespersons to only see their own opportunities, you can set their Access Rights on
Sales --> User: Own Documents Only.
You will find this setting in Settings / Users & Companies

Also, regarding your third question, the users in a team can create leads and opportunities, of course. 
I'd recommend to check their access rights.

Cheers,

Sales teams can sell diferent productos or services, or you can have sales teams by region. Besides this, sales teams can have a diferent flow or sales funnel, by having sales teams, you can assign an specific phase, i.e. "Demo" for an specific Sales Team.

Hope this helps.

Good day, Nguyen,

It's mainly for reporting purpose only buddy, don't waste your time. You need more code customization for it to work perfectly like other CRM (eg. salesforce)