Drifter, I'll try some of your questions.
2. and 3. No, a separate amplifier with a higher maximum power rating doesn't help the sound unless the speakers are playing so loud that the higher power capacity actually is used. Your 3311 should have plenty of power for your needs. The A1400-8 has been unavailable for some time and it's uncertain when or if it will be.
4. The major differences in how the center speaker and left surround were set would seem to indicate that those speakers were either defective or damaged so that they had to be set much higher to match the loudness of the other speakers. No, calibrating manually with an SPL meter doesn't give more accurate results than the Audyssey(or any other)auto calibration system. It adds human error in reading the meter, and, if anything, is less accurate.
