Two Issues: Extending Ethernet and Network Attached Storage

Issue One: 

My partner and I run a business from our home where she occasionally needs to hold hybrid meetings with groups: some online and some in person in our home. We've had problems with Wifi dropouts when she's doing this, because the router is in our home office and the room where she holds meetings is several rooms away. We want to see if we can extend Ethernet to the other room for these meetings, which happen monthly. As I see it, we have several options:

• Move the router from one room to the other once a month (this is how we've done it several times, but it's a hassle switching cables). We've also seen a cable A/B switch that might make this easier. 
• Find a way to extend Ethernet wiring via the home power network. We tried the commercially available Ethernet extenders that do this, but the noise on our home power network is such that the network only holds for a few minutes at a time. I'm not optimistic this option could work. 
• Run a long Ethernet cable from the home office to the other room, about 50 feet.
• Have two modems in the house and switch between them, but I'm concerned Comcast would charge us for another line even though we're only using one at a time. 
• Get wifi extenders and see if they're more reliable (this is less attractive because she's adamant about a wired connection being more reliable, and I agree).

Any recommendations appreciated. 

Issue Two:

We want to install Network Attached Storage so that we can share files via Wifi -- at present, we pass around a portable hard drive. I realize it's more complicated than just plugging the portable hard drive into the router via USB, and that we need an Ethernet connection for that. I tried connecting the drive to a dock that is connected to the router via Ethernet, but didn't see the options I needed to set that up in the router's setup/admin page. 

Does anyone here have experience setting up NAS for file sharing? I need some recommendations on equipment, etc., hopefully within our small (!) business budget. 

Thanks!

Brent