So from what I've read and taken into account from my studies of the Soviet Union and the revolutionary period prior, the Kulaks were effectively a cheap easy term that was effectively used to blanket label a very large amount of people.

So for example it made little to no distinction between a farmer who had seriously made it rich and owned a full in manorial estate and a much poorer peasant that owned 2 acres of land and 5-6 cows. They were effectively demonized for simply taking advantage of the stolypin reforms when they came about. Stalin and the party effectively saw three classes of peasants which were the bednyaks, serednyaks, and Kulaks respectively. They also scale respectively in what the communists believed was wealth. The term kulak eventually came down to people owning more than their neighbors being considered a Kulak.

So the reason I say all this is due to the fact the term "Kulak" was full of ever shifting goal posts to tow Stalin's line. So no I can't really give a solidified answer in whether they were abusive to other peasants due to how broad the term ended up being.

Now if we take a look towards the revolutionary era and before, I don't think this can be seen as characteristic of what peacetime Russia should WW1 not have occured or Russia not been involved. The new classes of peasants didn't really have much of a chance to establish any serious day to day to really give off a pattern in abuse before the metaphorical Russian ship sank. They had from 1906 to 1914 of peace which is 8 years which isn't able to really give enough of a time period to establish habit or any pattern of abuse towards other peasants. From 1914 to 1923 Russia was effectively thrown into absolute chaos and Russian society effect collapsed. It doesn't help that when war communism was announced and the peasants were effectively fleeced or had their grain outright seized to help during the civil war. The peasants who resisted were labeled as Kulaks and it was announced a "class war" against them. Just shows how it was pretty much everyone who didn't agree with Stalin or the revolutionary government being labeled as such.

They lost between 9 and 10 million people during WW1 and then on top of that, another 7-12 million people during the Russian revolution. If we take the high estimate that's 22 million people. Any characteristics of abuse can be seen of any facet of society in Russia. The entire period is pretty much untested ideology and human error or fanaticism brutalising or destroying Russian society for the better part of 20-30 years if we extend the chaos to Stalin. If there are patterns of bad treatment and abuse, they have been either washed away by the fact everyone was doing it not just the Kulaks, or by the fact the entire classes was effectively broken by Stalin during collectivization.

Robert Conquest (2001). Reflections on a Ravaged Century. W. W. Norton & Company. p. 94. ISBN 978-0-393-32086-2. Retrieved 3 January 2013.

Lynne Viola; et al., eds. (2005). "The War Against the Peasantry, 1927-1930 : The Tragedy of the Soviet Countryside". Yale University Press. Retrieved 2018-03-26 – via ProQuest Ebook Central.