The reason Taliban blew up Buddist statues was not because they were Buddist - they were images & Taliban's form of 'pure Islam' forbids these. They were making a statement in that act - it lost a lot of support for Taliban & contributed to much of the feeling of 'good riddance' felt by many Muslims & most others.

Contrast Taliban extremes with Turks who whilst renovating Haj Sophia (or what ever the name is they have for what was the great cathederal in Constantinople (Istanbul) that became a Mosque) found vast images in mosaics of Christian icons (Mary, Joseph, Jesus etc:). The leaders of Turkey at the time (a couple of hundred years ago) instructed the workers to cover up the images & say nothing as there would come a time when the building would be shared again - now the mosaics are fully restored & the building a museam - a testimony to enlightened Islamic rule & foresight - something the Taliban totally lacked.

Re the Shia & Sunnis. The main & most important philisophical diff twixt them is the issue of religious succession...

Sunnis follow 'the tradition' of an elected Caliph who is ruler rather than religious head. The Shia believe in religious succession from the Prophet and claim that Mohammad himself endorsed succession in speches he gave & that he named his cousin Ali as 'family' and the one to ultimately follow. So the split is over 'Tradition' vs 'The Family' in terms of spiritual and national leadership.

Because Shia don't accept the Sunni succession they have a reputation as 'rebellious' & 'quarrelsome'. They are more prone to challenge the Caliphate.

From early days (5th Caliph) they were persecuted & hounded for their beliefs & thus many of them adopted a self-protection mechanism of denial whereby they will publicly refute their beliefs as Shia but privately carry them on. For this they are called 'deceivers' by the Sunnis who say you can't trust a Shia.

The Sunnis are by far the majority (possibly 85% of all Muslims).

The Shia ritual of cutting their heads & parading & slapping the cut forehead is in memory of the murder of Ali's (4th Caliph) son by the 5th Caliph's soldiers. The 5th Caliph, named Mu'awiya was of the Umayyads (an Arab clan). The Umayyad line of rulers is one of the great lines.
Mu'awiya is accused by the Shia starting the intense persecution of them. He was also probably one of the greatest Caliphs in terms of Islamic growth and acendancy.

Cheers

Doug