Default [Q] Debranding/RSPL question

Hello, bit of flashing noob here. I'm preparing to debrand my Mozart as I am not able to upgrade to 7.8 through simply updating or using the force update tactic on zune.

I have read many guides of how to do this, of which this seems to be the most comprehensive:
http://forum.xda-developers.com/show....php?t=1002391

I have got all the prerequisites required to complete this process. However I have also heard a lot about RSPL/HSPL, which is not mentioned in the guide above and despite a fair bit of research I still do not fully understand it.

I suppose my question is
a.) do I need RSPL to debrand my phone or do I just follow the guide posted above^
b.) if I do need RSPL, at what point in the updating process

I'd greatly appreciate answers in the 'debranding for dummies' format :P

Thanks in advance.