Not a historian so I'll just give some short answers for time being, hope someone knowledgeable will answer better.

It was starting as the conflicts between different traders as magically Jews took trading and banking into their hands: Greeks vs Jews, old believers vs. Jews etc. The real problem started with the death of Alexander II(killed by the revolutionaries), and the subsequent domination of the right-wing conservative and reactionary ideologies, which were inherently antisemitic. The government was indifferent to the antisemitism and pogroms and some local officials like heads of police, for example, even supportive. With ever existing antisemitism in the society, it was very easy to incite the hatred with some rumor etc. Also, many Jews, being mistreated by the government, rose against it and became revolutionaries, to the point that in people's eyes it became interchangeable - revolutionaries = Jews and Jews = revolutionaries. Also, there was a huge frustration with the Great reforms that failed in many ways. So, with the reaction to the failed reforms and society painfully changing the Jews became the ones to blame and vent the frustration on.

Pogroms looked like a bunch of morons destroying the stores and trading places of Jews, going into the Jewish districts and synagogues and beating up everyone on sight, including women and children. Soldiers were to calm the unrest when it already was almost over, not really doing anything. The aftermaths were destroyed markets and stores, dozens of injured and few dead people, liberal outcry in the country etc. Jews and supporting young Russians were creating self defense groups.