I think I may be able to help explain the signal strength / quality.
The signal strenght is the raw RF power received by the OTA receiver not taking into account any noise or errors.
The quality is the measure of the digital modulation that occurs to the RF channel. Basiclly this indicates lost/unusable bits, the more you lose the worse the quality, when too many are lost you get video/audio problems.
You can have great SS and poor SQ and still have a good picture, and vice/versa. If you live in an extremely noisy RF area you can have great signal but your local interference can hurt you as described below.
You need to look at is the C/I measurement this indicates the difference between the intelligent data on the channel and general RF noise. If this drops your quality will take a hit and you will begin to notice more audio/video issues. So you have 3 seperate items to deal with to get good picture, SQ which is dependant on SS and C/I cooperating with each other.
What would be nice to know is the measurement units and recommendations are for each measurement. Voom CSR's won't know this, you would have to get this information from an engineer..
I hope this helps and not confuses more.
Chris.. =)