Planning on starting a DIY basement remodel. I am planning to do the DIY stuff and and GC'ing the items I don't want to do.

I am planning the insulation and framing phases and I have 2 questions:

1. Has anyone used I-joists (engineered wood joists) to build the HVAC/Plumbing/electrical soffits? It seems it would be way easier than using stick lumber or metal framing. Any details or pictures on how it worked or didn't work would be appreciated

http://www.lpcorp.com/ijoists/whylpijoists/whylpijoists.aspx

2. Has anyone recently used Foamular or other XPS (Extruded Polystyrene Foam) sheets to insulate their basement? I understand that some local building inspectors don't like XPS glued on the walls? Any details or pictures on how worked or didn't work would be appreciated.

XPS adhered to the walls is an excellent way to insulate a basement. Adhesive only works well on unit masonry walls, such as block. There are typically too many irregularities in a poured wall for it to hold. In that case, use mechanical systems--such as concrete screws through fender washers. Ideally, seal all joints with tape and use foam where necessary to ensure that as little air as possible is able to circulate between the foam and the foundation wall.