A) 16:10 is more of a PC aspect ratio (is the ratio of 2 A4 pages placed side by side). 16:9 is your typical TV format. If you are playing PC games, it doesn't really make a difference as you can choose your own resolution. For console/tv, either your image will be stretched or you will have black bars at the top and bottom of the screen.
B) Any screen that is 1440x900 (or 1680x1050) is 16:10.
C) All the screens you have listed, while they might support a 1080p signal, don't have 1080p panels. 1680x1050 is fairly close, but still falls short. Any that do support a 1080p signal will have to downscale the image. Just note that the 26" screen, while it is 720p, has a 1366x768 panel. This is pretty common in 720p tvs.
D) Unless you plan on sitting close (or using it as a PC monitor), 1080p on a screen less than about 40" is fairly pointless at comfortable viewing distances. I personally have a 24" screen which is a pc monitor that does 1920x1200, any more than about 1.5m away, while I can still read the screen, the detail really starts to disappear.
E) Generally, the lower the better. I can't comment on how 3ms difference affects it though.
F) If you are buying it as a TV, 16:9 is the way to go. Consoles, broadcast TV, blu-ray, etc... all are geared towards 16:9 aspect ratios. I purchased my screen as a monitor, so while I do use it for TV and consoles, I just deal with the fact the image is streched.
G) I'd prefer the bigger tv since the panel in the 19" will only be 1440x900. Any advantage would be lost due to the smaller size.
