Looking for Software...

Now I have my Robo 3D working, I want to use it to make things for my N scale model RR. Things like buildings, rolling stock etc. I need something easy to learn/use. I found one stone house but its SOLID, I would prefer the model be walls w/o solid core. The roofs can be separate parts.

One thing that would be nice is be able to use photos of what I want, say all 4 sides and turn them into useable files.

thanx in advance........