Opinions will vary, but I had used Punch! 5 in 1 Home Design back in 2004, and was pretty disappointed. Too many design limitations. Not sure about floorplanning version. I guess the only way to really know is try it yourself.

I'm happy with AutoCad, but it's definitely not casual-user friendly.

google sketchup, its free, pretty easy to learn, and is a 3d modeling software if you look in my signature under stuff ive built, there is a portfoilio of work, towards the end is sketchup stuff that i did awhile ago, but the best part is its free, and you can get a feel for how things will look and fit together

Even if you can convert (looks like you can) it more than likely won't come out like you want. AutoCAD is very touchy and doesn't like other software to be imported. However, exporting from AutoCAD to other types of software usually works just fine. But, I say print what you draw in sketchup and take that to a draftsman for them to turn into a working set of drawings. Then take that to an Engineer.

For permits, depending on where you are located, you usually don't need a lot of info. I once took a simple floor plan and two elevations of a restaurant kitchen to get permits and all I had were two dimensions on the entire thing. We were remodeling the local Moose Lodge. All they care about is that it's not hand drawn.

An Engineer needs lots of info on the drawings like details of how things attach, sections, anything that shows load, structural sizes, dimensions, etc. They typically don't need to see a 3D rendering. If you can show all of this in sketchup then you are good to go. If not, then you'll definitely need a draftsman.

Hope that helps.

Randy