After a lot of cogitating, I narrowed it down to a paint scheme I found on the Sherwin Williams web site on their Victorian paints page, then headed off to our local DIY store to see what I could turn up that would match. I came home with several match pots, and painted lots of index cards so I could see what the colours looked like when they dried, and when taped to the house in natural daylight. Most of them weren't what I wanted, so I went out again today and got some acrylic craft paint in a few more shades. Eventually I have narrowed it down to dark brown for the roof (two colours under consideration), a blue-green for the house (similar to the historical colour light blue stone) which I can only get close to in a kitchen-bath paint, and brown or terracotta for the trim. Please note that these are not my personal choice at all, but they seem to be a good compromise between historical accuracy and a scheme I can live with. This is such a big decision, as the colour will really make or break the attractiveness of the house. I'm still not sure about these colours, I am going to live with them for a few days and see how it goes. But I know the house will look more realistic, and less like a toy, if the scheme is accurate.
In the meantime, I built the porch steps (Step Q.f) and applied the porch foundation trim (Step S). I had to relocate the steps to the middle of the porch as that is where my shop door will be. They went together similarly to the stairs in the house, the only real difference being that you glue on all the risers first, then add the steps second.