Got a couple of OTG cables from Amazon.
Mine weren't shipped from Hong Kong, though these are the ones I use.
I use them with an SD card reader, but they work just as well with my flash drives.
Only "problem" with my Sero 8 is a charging issue.
Both my phone and Sero 8 are running 4.4.2. Don't know if there are differences, in the UK, but I'm willing to bet they're are and possibly significant.
The photos on my flash drive, connected with the OTG cable, show up in the gallery app and the documents show up in the office app.
My Motorola phone has no settings to move photos to an SD card. My preferred method of moving files is with the ES File Explorer, from the app store. I also use it to move files between devices by synching it with a Dropbox account.
Both the ES File Explorer and Dropbox are 2 apps that I'd suggest you add to your Sero 8 to help your file management.
Some of the more tech savy folks may have other ways, but these are the simplest for me.