[Question(s)] Current State of Model Editing ?

[Emmique]

So, used to be doing model swaps and a few reskins back in WotLK when it all seemed to work quite easily.
Now in Cata however, went to open up the MyWarcraftStudio and it just keeps crashing on opening any of the files, along with the WoW Modelviewer not working, for MWS finding it a bit tricky to find an updated version currently.
Have had a quick look around, but any already excisting explanations to me seem a bit vague...

Anyhows, I know how they have changed the file formating of the patches around, but with such I have a few questions.

1. (Patch 4.2+) Is it still possible to edit straight into the file, as in not having to keep re-morphing using a morphing program ? And if so, then how exactly do you go around to doing such these days, what programs what methods ? As well as once the edit is added, how do you go about removing it for new patch updates etc. etc.

2. (Patch 4.2+) If you have a couple of reskins available, how would you add them into the game files now ? What programs, since quite obviously the make a patch drag and drop it doesn't work anymore ;/

3. (Patch 4.2+)Is it at all any more detectable now ? Since you would have to go more in-depth into the patches to make an edit that would stay... ?

Thanks to anyone who can answer any of these