The A550 has a CMOS Exmor sensor like the A500. It is not the CCD from the A350/A380. While it is reasonable to assume the A500 will have similar image quality to A700, the A550 could possibly be better as it is a new sensor.
As far as I can tell, there is no AF at all in precise LV mode, but then again that's why they give you the quick AF LV mode...
On the viewfinder, it is improved from the 0.74x of the A350, but still smaller than average at 0.8x compared to for example the 500D at 0.87x.
_________________Canon DSLRs: 7D, 5D2, 1D, 600D, 450D full spectrum, 300D IR mod
Lenses: EF 35/2, 50/1.8, 85/1.8, 135/2+SF, 28-80 V, 70-300L, 100-400L, TS-E 24/3.5L, MP-E 65, EF-S 15-85 IS
3rd party: Zeiss 2/50 makro, Samyang 8mm fisheye, Sigma 150 macro, 120-300 f/2.8 OS, Celestron 1325/13
Tinies: Sony HX9V.