Need help to make Office Network

Hello

I am going to make changes in my office network and need your advice on this project.

I have 7 Offices. One is the main office and 6 are branch offices.

I bought Mikrotik routers: for main office CCR1036-12G-4S ( MikroTik Routers and Wireless - Products: CCR1036-12G-4S ) and for Branches RB750G ( MikroTik Routers and Wireless - Products: RB750G).

Also, I have shared VPS in the main office and want to access from the branch office.

I have some experience in networking, but I need help to make this project with high-grade.

I also made simple topology in packet tracer with Branch and Main Office.

  1. Which subnets I need to use in each Office to avoid any conflict or issue?

  2. Please advise me Which VPN connections are good, do I need to install a new firewall or can I use Mikrotik firewall.

  3. Will be it good to make Vlans? Every advice will be good for me.

  4. I want to connect all branches to the main office with a VPN. If is it possible From branch PC to go Internet through the Main office and how can I do this.

Thank you

Hey there!
This link shows information about VLANS
Hope it helps