Regarding #51: in today's 14.10 daily I was affected by the same problem. I copied /usr/lib/syslinux/gfxboot.c32 from my 14.04 system into the usb /syslinux and it now boots fine.
This is 14.10 Ubuntu 64. The boot disk was created on a 14.04 Ubuntu 64 system, up to date, with usb-creator-gtk.
Regarding #51: in today's 14.10 daily I was affected by the same problem. I copied /usr/lib/ syslinux/ gfxboot. c32 from my 14.04 system into the usb /syslinux and it now boots fine.
This is 14.10 Ubuntu 64. The boot disk was created on a 14.04 Ubuntu 64 system, up to date, with usb-creator-gtk.