Is there a need to have autoboot or is that just a preference?There could be a couple things causing this. The roms could actually be invalid; try using different roms for those games and see if they work. Your SD card could be fake. You can check the validity of your SD card with H2testw.
Nope. You can boot Gateway via the MSET exploit or the web browser on 4.5. You only need a firmware version with themes if you want to be able to autoboot into Gateway/CFW.