Bandwidth Usage (NAS VPN)

[Nem]

I just wanted to confirm if any of the following scenarios would consume my monthly bandwidth. I added a bunch of things to my NAS (running OMV) and I'm way over my monthly bandwidth limit and didn't know if the two were related or not, so just wanted to clarification...

I have OMV on a NAS on my local network. On the network there are 2 windows desktops, and 2 laptops. I use the following plugins:
Deluge
Plex
Couchpotato
Sickbeard

I also have OpenVPN server set up on the NAS. This way, the laptops can access the NAS when away from home.

However, the NAS also runs an OpenVPN *client* and I use that to connect to a VPN service (FrootVPN). So the machine runs both a client to connect to FrootVPN, and a server so my laptops have remote access.

Due to the fact that FrootVPN changes the NAS's IP, I had to set up a ddns updater (ddclient) on the NAS, and have that update a host on noip.com. The only way for my laptops to connect to the NAS remotely is by connecting to "domainname.com" in the openVPN config. "domainname.com" is always tied to whatever IP FrootVPN assigns my NAS because of the ddns updater I mentioned.

Recap: the laptops connect remotely through "domainname.com" in the oVPN config file, but my local desktops still go through 192.168.1.xxx:port whenever I want to access OMV or any of my plugins. The NAS itself is hidden behind FrootVPNs service

I feel like my monthly bandwidth usage has been going up ever since I set up openVPN, and hid it behind FrootVPN and I'm wondering if thats possible?

Specific questions (I know these are pretty simple but I want to be sure of the answers):

1. If I use my laptops remotely and connect to the VPN server on the NAS (using "domainname.com"), will my home bandwidth be used up if I DONT open any files? Of course bandwidth would get used up if on my laptop I opened a video file for example, but what about if the VPN connection is up, but I don't directly access any files?
2. On my laptop, if I go to domainname.com:32400/web to access plex remotely and I play a video, am I correct in thinking that home bandwidth will be used to send the video?
3. What about, as in #2, I access plex remotely through the VPN but go to 192.168.1.xxx:32400/web instead? Does bandwidth still get used at home? So accessing through the local network and not through the domain...
4. On my desktops at HOME, will bandwidth get used up if I play a video through plex by going to 192.168.1.xxx:32400/web? (unsure about this one but I dont think so)
5. Likewise, on my desktops at HOME, will bandwidth get used up if I play a video through plex by going to domainname.com:32400/web?

I think I understand 1-3, but would like some clarification as to what happens to my home bandwidth in cases 4 and 5.

Most of these questions are fairly simple, but I think I made the situation more complicated by introducing FrootVPN, a ddns upater as well as running my own VPN server on the NAS on top of that. I'm unsure how bandwidth is getting distributed now

thanks!