1. 7-speed freewheels in either the compact or standard version will work on a 126mm hub.

2. 8-speed freewheels will work on a 126mm hub with minor adjustments to spacing. This setup tends to be over-dished. Its best to use and offset set or to space up to 130mm. Idealy 130mm spacing and an offset rim is best

3. While Campys bearing quality was the best available until New Dura Ace arrived in 1985, @ 1/1000 tolerance it certainly wasnt exceptional. IIRC 1/1000 = grade 100