Wow, I am really suprised that nobody has any info to offer me. After seeing all the people who are flashing their phones I figured there must have been others around who were trying to modify the firmware that would be willing to offer some advice, anyway...
If anyone is interested I have managed to work out how to modify the default network settings so that only those I want are visible, having done this though I am now very eager to go deeper and really start modifying the firmware and removing all signs of branding, next I will be going after the locked content, I really want to be able to delete the default stuff, or maybe even modify the firmware to install other content (not superlocked) instead of the default stuff.
So if anyone happens to see this and has some info that might help me out I would appreciate it very much. I am particularly interested in knowing what the difference between different language firmware is, is it just a matter of default language or are there other hidden settings that are specific to the country of origin?
If anyone wants to know how to remove the preconfigured network settings just let me know and I will write a quick guide for you, the current method allows you to preconfigure up to 4 connections (when using Z510AIEL2_xxx), I plan to change this but for now it is a suitable solution. I haven't looked at other language firmware as I don't have any, I would really like and english firmware plus other languages, this way I could check for the differences myself.
Cheers.