Q1. Creating an MP4 is pretty much universal.
Q2. One method is to use Compressor as it allows fine tuning.
Regards USB (thumb drive) it will need to be formatted to something the target player can understand. I'd run with FAT 32 for a more universal starting point. EXFAT for larger files but I've found this to be less compatible with TVs etc.
Try the Computer setting and adjust the Resolution down from 1920x 1080 to create smaller files that are MP4 friendly. If you require 1920 x 1080 then Compressor will assist.
Al