Mount script cannot be created. mount: No such file or directory
Wat are you using to create and format your partitions? I ran into a similar error when I used Paragon Partition Manager (https://www.paragon-software.com/) in Windows. The phone wouldn't correctly recognise the partition.

I then used (I think it's the 'official') the SD Formatter program in windows to format my partition but it only seems to make use of the entire sd card and not really give you an opportunity to have multiple partitions.

You should really try GParted. It's pretty fool proof. Just make a bootable USB, pop on GParted and create and format you partitions in that. Good guide here for a GS4 but should work for your phone too: http://forum.xda-developers.com/showthread.php?t=2285221