Hi Luca, it's not really a full wireframe mode, but on Petr's page here:
http://kyticka.webzdarma.cz/3d/moi/#WireFrameDisplayMode
there is a script that you can set up which will hide all faces leaving only edges being displayed.

It will kind of give you a quick wireframe display but you can't really work on it very easily because things like selection doesn't work very well when no faces are displayed.

I do want to add a proper wireframe mode in the future but it will require quite a few changes to selection, it is not really just a simple change to display only.

One thing for now - make sure you have the options for "Display hidden-line curves" and "Display hidden-line edges" turned on in the Options dialog, under the View section. That gives you a lot of the abilities of wireframe mode even in shaded display because lines that would normally be hidden by the surface shading are visible in the faint dashed line style and can be selected similar to a wireframe display.


re: Quads only option - that is also something that I would like to try adding in the future at some point, but it would involve creating quads that followed trimming boundaries instead of following the natural UV layout of the surface. Unfortunately that's a very difficult thing to set up, it is much more natural from a NURBS processing perspective to quads that are aligned to the UV structure of the surface rather than at any random angle.

- Michael