I just finished ERA 797, and I did it with my three young kids (7/7/9, two girls and a boy). First, if you can take apart a plane, this will be no problem for you. My mechanical skills are not stellar and I had no problem. The ERA kits go together very well, and there is ample help available on this forum and from ERA. On the space required, all you need is one garage spot. A little room around the car is nice but you can do it in a fairly confined space. I would absolutely recommend having the kids involved. Mine loved it, though it was easier working one at a time vs all three. I would set things up beforehand and have a task ready so they could get to work and accomplish something solid in about an hour. It was one of the best things I've ever done. I also had a white board so I could explain things to them (and they would also draw pictures on it). My build log is:
Lippy's ERA #797 build log
And yes, I would go with ERA again. It's not inexpensive, but you get a good quality product and support and will be happy with the results.