Re: Multiple monitors with different sizes and orientations: how?
Don't know about three monitors, but for two screens and NVIDIA video my experience is that it is impossible to have different orientations (i.e. one monitor in portrait mode), 3D acceleration, and one single desktop simultaneously. The reason is that NVIDIA drivers do not support XRandR 1.2 which would make this possible.
Your choice is:
a. Twinview, with full compositing and a single desktop, but no way to rotate one monitor only (you can rotate but only all monitors together);
b. Two separate Xscreens with Xinerama, but Xinerama disables compositing (so no Compiz or Kwin).
c. Two separate Xscreens without Xinerama, in which case you get compositing but no way to move windows between the screens (though the mouse pointer will cross the boundary).
ATI might (probably is) different in that it supports XRandR 1.2 from what I've heard. NVIDIA have promised same for years but not delivered.
Desk: openSUSE 12.3, KDE4.10.2, Intel i3, 8Gb, Kingston 64Gb SSD, 2 SATA, dual monitors.
Lap: Toshiba Satellite L300, openSUSE 12.3, KDE4.10.2, Intel C2D 2.1GHz CPU, 4Gb, Intel X3100 video.