Larry,
There are many more knowledgeable than I who will happen along shortly, but in the meantime ...
You mention the windowwall is north, which is your screen wall? Yes, I would think that the windowwall in the daytime, and the light at night, will make a FP setup difficult. There are screens that reject ambient light and enhance contrast more than others, and that may prove satisfactory with a fairly bright projector. The new Sony black screen looks very intriguing/promising (although I'm currently boycotting Sony over their absolutely outrageous root kit issue).
There are many more knowledgeable than I who will happen along shortly, but in the meantime ...
You mention the windowwall is north, which is your screen wall? Yes, I would think that the windowwall in the daytime, and the light at night, will make a FP setup difficult. There are screens that reject ambient light and enhance contrast more than others, and that may prove satisfactory with a fairly bright projector. The new Sony black screen looks very intriguing/promising (although I'm currently boycotting Sony over their absolutely outrageous root kit issue).