Do you know what kind of sound board you'll be working with? I work extensively with the X32 and M32, and both have the ability to do a two track recording via a USB stick. Some may have SD card access, as it's an optional accessory for the boards. The new Behringer Wing has the SD card built in. If possible, 32gig FAT32 formatted is what I would be prepared for as the x/m32 don't necessarily like larger cards.
The H4 essential has two xlr inputs that would be fine for an analog output from the board. I would have no issues using some extra outputs to give you a signal. If the band has a large number of monitor mixes though, it might be challenging. I'd be prepared with a pair of both XLRF -> XLRM and 1/4" TRS -> XLRM cables just in case.
Good luck!