Can I softmod again using the guide on this site on top of what I have now, as I've softmodded before from youtube? Will it just overwrite everything or do I have to revert my wii back to any state before doing so. Thanks.
It will just overwrite whatever you did before.
[spoiler=Click here for useful links]Softmod any Wii guide Yes ANY Wii!!!
FAT32 Hard Drives - Formatting, Loading, Ripping, Playing (recommended USB setup)
Ultimate List of Troublesome Games & Solutions
The Noob's Guide To Getting Help
How to Run & Post a System Check
Blackscreens & Freezes - Causes & Solutions[/spoiler]