Sir how is AV shielding done? I've read that these magnets can affect other electronics.
The magnet basket is enclosed with lead, aluminum or some non-magnetic basin.
I've heard that neodymium magnets require a long break-in period but once achieved, it really outperforms other types? Is this true?
Magnetics and electronics do not require break-in, contrary to common misconceptions. Only mechanical devices need break-in. Like motor vehicles. Admittedly, speakers are electro-mechanical devices. The rubber or foam or cloth suspension and spiders perform a mechanial role and may benefit from a break-in period. But not the magnets. If at all, the magnet will decrease in flux strength over time. And that's no good.
Just a note. There is no break-in period that can make a lousy speaker out of the box sound better over time. A good speaker is always good right out of the box. IF it becomes better over time, the mechanial compliance of the spider and the surrounds may have benefitted from this "break-in" period. But this can also be psychological. As the human mind can grow accustomed to the sound over time.