Sorry I don't know the answers, but I must say I, and probably many others, are thinking of taking pictures and sending them elsewhere for further use and processing.
I don't have my RPi yet, but the list of software you mentioned looks pretty familiar. For a security cam application on a typical high end Linux box, I note Zoneminder is quite common. For more resource-restrained environments, the motion app seems highly recommended. I'm hoping motion is a good choice.
One other thing I can think of, again not having the actual hardware yet, is that we'd like to use the "Class 10" SD cards for speed reasons, but some notes I've seen say Class 4 is a better choice for compatibility/stability reasons. So basically, between CPU, RAM, network and "hard drive" (the SD card), the limiting bottleneck might be the SD card. If the images could be sent directly across the network, the whole thing might be faster. Just a guess; your mileage may vary