Here's an example from Solidworks 2016; you just have to make your sheet metal parts in the welded construction and for the MEP done as usual by choosing the component
You create a profile of your folded sheet metal 160 x 45 and use it as a welded construction profile
On the other hand, you won't be able to unfold any element since it's not sheet metal strictly speaking.
Personally, I also make frames in folded sheet metal, I make my parts in sheet metal and then I assemble them in an assembly. A bit tedious, but it depends on your needs in fact
The surface, I don't know too much, but when you unfold it calculates a developed?