New Website (Single page edit and a members area)

Hello All,

For various reasons I need to upgrade our website to make it more scalable on mobile devices (how I look back on fondness at days when all we had to design for were IE and Netscape). Anyway, I will probably use the opportunity to jump straight into Drupal 8.

Before I start planning I want to add two new features to the new website and I wondered if these two features were possible within Drupal standard or through the use of existing modules?

1 - Give users permission to edit one single specific page.
I run a charity website and I want to set support group pages up, then give that group volunteer access to be able edit their group page only (but not other group pages).

2 - Members/Paid area.
We want to set up some reward content (conference video clips for example) for members of our charity as a thank you for their donation. Is it possible to setup a paid area where users can pay (perhaps using Drupal Commerce) to access the members area or where I manually give users permission to access the members area.

Thanks.

Ashley.