KillWillI ended up getting the SanDisk 200GB, in case anyone is looking for a micro SD for their M1. So far it works great, and it was pretty cheap, too ($120 CAD)...
TSaymanYeah, you'll need a micro SD card to use this. The only internal storage is the ROM the firmware is stored on, and that's not user accessible.
I personally use a SanDisk Ultra 64 GB card because I had an extra one and my library isn't that gigantic. I plan on upgrading to a 128 GB card as I expand my collection though.
TSaymanThere are instructions on the site you download the firmware from, but essentially yes. You just unzip the firmware to the ROOT LEVEL DIRECTORY of the card. Once it's in your card's root directory, boot the player and go to System Settings -> System Update.
This looks for the firmware on the card, reads it into memory, then writes it to the ROM and reboots the player.
I'd be wary about upgrading to v2.0 for now as I've heard it introduces performance issues and can cause the player to freeze outright. I've got v1.12 and it works great for my purposes.
The firmware comes in a RAR file, so you'll need 7Zip or WinRAR to unzip it