1. Yup, I'm aware and OpenVPN does work on the Neo U1.
2. I own a couple of hard disks (1 TB each).. Phillips and some brand name that's "washed off" and I can't seem to recollect the brand. Also a couple of thumb drives (8GB, 2 16GBs, a 128GB & a Samsung 256GB USB 3.0).. Plus a 3TB WD external HD with its power brick. All these USB drives have been tested and function satisfactorily on the Neo U1. Partitions are either FAT32 or NTFS format.
3. EXT4 support is definitely available on the Neo U1 too.
4. Very true... Guess you may need the extra storage space then. Do prioritize properly.. graphics intensive games may not display or "play" properly if being read of a slower memory than smooth performance demands.
5. Okay.
6. Totally understood... However, Minix tends to ship their devices as close to stock as possible.. The biggest sized pre-installed app would probably be the XBMC For Minix app. I strongly recommend you leave that installed due to optimizations by the Minix devs.
You are welcome... Tis true that the Neo U1 is a bit pricey, but it does come with certain perks... I.E a manufacturer that stands by its box and a thriving community. Hey, even at its price point, its still much cheaper than say the Nvidia Shield Box powered by Android TV...

Yup, nvidia shield cost almost double the price of Minix.