1. What was your estimated price per sq. foot total? I estimate I spent $100-$120 per square foot. The reason I do not know exactly is that I have never gone back and added it all back up. I had a contractor who did the work. If you contracted it yourself, you could possibly save some there. My contractor was worth every penny though, because he knew things I did not. Nevertheless, had I had the time, I believe I could have done some of it more cost effectively.
2. How much did you pay for each 40' container? Almost three years ago, I paid $2,500 per (45') container delivered to the site, but not including the crane to set them on the foundation. I used three containers, side by side. Container prices vary with supply and demand and who you buy them from.
3. Roof Trusses, any problems? Roof trusses were no issue. The building supply place orders them to your specs, delivers to site, and never touches them. You can see the original plan on the blog. I had some extra corrugated Quonset hut material I planned to use, but the engineering was going to cost so much to get it to code, it was not worth using. The combined cost of the trusses and the metal roof were less than the engineering necessary to make the salvage material work (see #4). Also, I think I got a better roof with the truss and metal design. The beauty of using the trusses is that I not only have insulation inside, but have blown in insulation in the attic space created by the trusses. Better planning could have saved me some money. For example, it cost appx $1k or more to get a crane to the site each time. I brought one in to unload the containers off the truck and on to the foundation. Had it been a slab foundation, I could have had the containers delivered on a roll off unit and avoided the crane. I'm not sure how I could have done it, but if the trusses were there at the time the containers arrive, you could use the same crane to set both. Again, it is a planning process, which I did not do nearly as well as I could have.
4. Any budget costs you would mind sharing? My goal starting out was to build a house for $50 per square foot. It was the first time I had built a container house, and the first time the county building inspector had encountered one in our county. An inspector may be, but is probably not an engineer. There are regional building codes that many counties subscribe to. If the inspector can find your design in the standard book, there is virtually no question of acceptance. If he cannot find your concept in the book, he will require a professional engineer (PE) to submit the design and sign off on it. That has liability implications for the engineer, so he will over design it, and he will charge you professional fees (like a lawyer or doctor) to certify your design. The foundations was tremendously overdesigned. I believe I could stack three containers high on the foundation I have, and be totally stable and safe. Since the engineer did not have any experience with containers, he had no clue what cutting some of the walls out might do to the structural integrity of the container. Therefore, he put a block foundation under every inch of every side of each container. The foundation cost $6k. I think a slab or piers would have been fine. Either would have been cheaper, but the piers would get the containers up so HVAC, wiring and plumbing could be underneath (as my foundation did for my building). All that would have to be put in or under a slab design. The engineering for using the Quonset pieces was going to cost $6k and the material for tin and trusses was $5k.
Another thing I really was enthusiastic about was re-using as much building material as I could. Habitat's Re-Store supplied my kitchen cabinets, toilets, bathroom sink, kitchen sink, all exterior doors, some interior doors, dishwasher, washing machines, etc. (new windows and tubs). When you are using salvage material and using a contractor, you have to balance the figuring/thinking time of the contractor to adapt the used article, against the ease and familiarity of the contractor with installing new stuff with complete directions included.
5. How many sq. ft heated/cooled? There are 1,080 sq. ft. heated and cooled. The porch is additional (16' wide and appx. 30' long).
Added comments: You did not ask, but I used an architect who was very interested in my project. He was very flexible. I could tell him my idea and he could translate it to working drawings quickly. I could sit for an hour and try to figure out how to lay out the bathroom. He could scratch it out in ten minutes and it would be exactly what I wanted. If I were building again, I suspect I would put two containers side by side and stack two on top. My house is 1,080 with three (45' not 40') containers. Four 45' containers would give you 1,440 square feet and four 40' containers would give you 1,280 square feet. You would have to calculate the extra cost of the longer containers for the space gained. I believe that if you have to have your foundation engineered, the smaller foundation footprint would pay. Additionally, you do not need the porch foundation to be as substantial as the rest of the house. Mine are all the same. As much as I have complained about the cost, though, I think I could take a direct hurricane hit, and possibly a direct tornado hit and not lose the house (only the roof). Since I did not let the contractor penetrate the top of the container, and sealed each container to the other, I could lose the roof and still not leak. Also, no matter what, get the high-cube containers whether they are 40' or 45'. The extra height allows you to frame it out and still have a roomy feel that height gives you.