Hi @greavette, first of all: I've also tested NethServer just for two month, but I'm trying to answer your questions as I'm almost in the same situation as you.
As far as I know a domain controller stringently needs to be responsible for DNS. I'm unsure with DHCP, but in all configurations I've seen the DC is also responsible for this.
Yes, it does.
I suppose your users use Microsoft Windows as operating system!?
Then you have to install and use the RSAT tools (https://www.microsoft.com/en-US/download/details.aspx?id=45520) on one of the Windows computers to configure this batch files for each user separately (or set a policy). If you're interested in details, I can create a short tutorial.
The personal folders are created by NethServer when a user first logs in. You can reach them by calling
with file explorer (replace servername, user and domain with your values). You can also add this as a home folder for your windows user and connect it e.g. as H: drive using RSAT. To my knowledge setting it as a policy is not possible because of the domain being part of the personal folder name. (When setting as policy it only allows to configure a base path for personal folders and in this searches for a folder named as the login of the user.)
The same as above: if you're interested in details, I can create a short tutorial.
Your question regarding the firewalls has to be answered by someone else. But if you set your DC as gateway, it think it's easy to configure access for each computer.