[Nix-dev] A few beginner issues

[Nick Sabalausky]

I'm new to NixOS (coming from various more traditionally-designed 
distros, like Debian and Manjaro), and trying to learn by working with 
it in a WMWare instance. I've gotten it installed into the vm instance 
via the live disc's gparted and "nixos-generate-config" and 
"nixos-install", mostly going by what's here:

https://nixos.org/nixos/manual/index.html#ch-installation

And I'm now able to boot into the newly installed, umm, installation 
running KDE4.

Now that I'm trying it out, there's a few things I'm having trouble 
figuring out, and was hoping someone could help me out with these 
examples so that I can have a better idea of how to work with NixOS.

1. I'm having trouble getting vmware guest additions to work. I followed 
the instruction here...

   https://nixos.org/wiki/Installing_NixOS_in_a_VirtualBox_guest

...to add the following line to my /etc/nixos/configuration.nix...

   virtualisation.virtualbox.guest.enable = true;

...but after I "nixos-rebuild switch" and reboot, the display manager no 
longer starts and dmesg includes this suspicious looking line:

   stage-1-init: modprobe: ERROR: could not insert 'vboxsf': No such device

I didn't need to add that line to configuration.nix before the original 
"nixos-install", did I? Or is something else going on here?

Luckily, I can just reboot back to the old working configuration, which 
is an *awesome* example of why I'm determined to learn my way around 
NixOS. But it would be nice to understand how to get these virtual guest 
services working.

2. When I'm in KDE4 on NixOS, I can change the display resolution, but 
the change doesn't persist across a reboot. Why is this? What is the 
correct way to make it persist? Haven't had this happen in other distros.

3. I added "firefox" (minus quotes) to the environment.systemPackages 
list in configuration.nix, did rebuild/switch, and it's now installed 
and works, BUT it installed Firefox Nightly instead of a firefox 
release. How would I go about installing a release instead of nightly?

4. When looking up the firefox packages, I noticed a 
"firefox-unwrapped". What is that and how does it differ from the 
package "firefox"?