I can't answer every aspect of your question, but I believe I can make a number of interesting observations on the topic.
Two communities
It is important to understand that the Eastern European Jewish immigration was comprised of two very different groups. Following the 1881 assassination of Alexander II, the anti-Jewish pogroms and the Moscow expulsion of Jews in 1891, approximately 1.4 million Jews fled Eastern Europe. Between 1880-1890, 75% of them settled in NYC’s Lower East Side. Thus: the first was a small group of young Jewish intellectuals, who had previously distanced themselves from their Jewish heritage and cultivated close ties with the ‘Russian Colony’ revolutionary movement. The second and larger group, were the impoverished Yiddish-speaking Jews, pogrom victims from Imperial Russia’s western Pale Settlement. Not knowing English, needing to make a living, these young Russian radicals were forced to occupy the same spaces as the larger, working class group.
Eastern European Jews and diseases
Thus, in the collective Jewish American memory, the Lower East Side is exemplar of the Jewish immigrant experience, attached to imagery of narrow streets, crowded tenements and congested factories. The tenements in particular are crucial: they were three or four story flat buildings filled with windowless closet-size rooms, built with no standards for minimum space, light or ventilation, housing up to 24 families concurrently and hosting an estimated 500, 000 by 1865. By 1890, 80,000 tenements were built in the city and housed 2.3 million - i.e. PRIME DISEASE ENVIRONMENT. Jacob Riis’ account indicates that these were the tenements that Eastern European Jews found upon their arrival in New York City and soon they too became synonymous with disease. The most famous instance of this is the 1892 typhus epidemic on the Lower East Side exclusively among Russian Jewish immigrants. The result was quarantine in the form of forcible removal to contagious disease hospitals, confinement to tenement rooms and temporary detainment specifically of Russian Jews at the Port of New York. While immigrants had long been regarded as dirty and diseased, this could be considered the defining moment in which Jews became tied to these stereotypes in the public imagination as a result of their ethnicity.
Work and socialism
The Lower East Side was also synonymous with the garment industry - which gave rise to the conflation of working and living spaces, specific to those of Ashkenazi Jewish background, through the creation of the sweatshop. Within the garment industry there were three systems and sites of production. In the mid-19th century, the family system, wherein work was done by family members in the home, was prevalent among Irish and German families. In the 1870s, home based work declined as factories became widespread. In the 1880s, however, the influx of Eastern European Jews prompted a new production system - the contracting or sweatshop system that existed to foster hyperspecialisation. A contractor, usually an immigrant who had been in New York longer than the freshest arrivals, would pick up unsown garments from the manufacturer and supervise workers in his own home or a tenement room converted into a shop. The finishing work was usually done by subcontractors, also within their own homes. This meant that the worst conditions of the factory and the tenement had merged into one, and indeed Jacob Riis’ influential account “How the Other Half Lives” mentions that “homes of the Hebrew quarters are its workshop also”. As such, the domestic sphere was interrupted by intense labour in already squalid conditions.
This, combined with the aforementioned seeds of radicalism in the form of the Russian Colony, meant that the Jewish community became EXTREMELY politically active:
-Official workers institutions/unions were erected e.g. United Hebrew Trades and the International Ladies Garment Workers’ Union
-The first major strike occurred on the East Side in 1886, shutting down the entire garment industry. Major strikes occurred almost every two years from 1890 to 1900; nearly every individual had walked a picket line, marched in a parade, or protested.
-Beyond official institutions, socialism and working class consciousness were disseminated through the Yiddish public sphere in cafes, assembly halls, parks
-Also crucial: Yiddish socialist lectures and 'soapboxing' - in 1913, Columbia University found that almost 32% of young Russian Jewish men attended at least one lecture per week, and no other immigrant group attended lectures in higher numbers.
-And Yiddish press: the Forverts, a radical socialist newspaper (still exists today as The Forward, though less radical) reached a circulation of 275,000 in the 1920s.
TL;DR
Basically, I'd argue that the radical ideology imported by the Russian Colony combined with horrible working/living conditions of the general poor Yiddish population of this particular immigration led to A) Public perception of American Jews as dirty and diseased immigrants (until they became "white" in the 50s, which is a whole different story) and B) Extreme democratic participation and socialist activism amongst American Jews (also until they became white)
Regarding conflicts amongst groups of Jews, it is worth noting that many of these exploitative garment capitalist the Eastern Europeans were rioting against were German Jewish from the 1840s immigration, though I don't have much detailed information on this.
Unfortunately, much of the legacy of the Eastern European Jewish immigration is forgotten today as a result of Jews' entry into the middle class and the Lower East Side is pretty much sanitised, but for a while it was truly the heart of American Judaism.
(more here: https://forward.com/opinion/356166/how-jews-became-white-folks-and-may-become-nonwhite-under-trump/)
Sources:
Bauman, John F, Roger Biles, and Kristin M Szylvian. From Tenements To The Taylor Homes In Search Of An Urban Housing Policy In Twentieth-Century America. 1st ed. University Park: Pennsylvania State University Press, 2000.
Boys, Bowery. "The Grand Tale Of Orchard Street And Life On The Lower East Side - The Bowery
Boys: New York City History". The Bowery Boys: New York City History. Accessed 3 May 2017. http://www.boweryboyshistory.com/2015/05/the-grand-tale-of-orchard-street-and-life-on-the- lower-east-side.html.
Diner, Hasia R. Lower East Side Memories. 1st ed. Princeton: Princeton University Press, 2002. Gray, Christopher. "Streetscapes/The Jewish Daily Forward Building, 175 East Broadway; A Capitalist Venture With A Socialist Base". Nytimes.Com. Accessed 3 May 2017.
http://www.nytimes.com/1998/07/19/realestate/streetscapes-jewish-daily-forward-building-175- east-broadway-capitalist-venture.html.
Hapke, Laura. Sweatshop: The History Of An American Idea. 1st ed. New Brunswick: Rutgers University Press, 2004.
"Hellraisers Journal: May Day In New York City! Unionists & Socialist Turn Out By Tens Of Thousands!". Caucus99percent.Com. Accessed 3 May 2017.
https://caucus99percent.com/content/hellraisers-journal-may-day-new-york-city-unionists-socialist- turn-out-tens-thousands.
"Home". The Forward. Accessed 3 May 2017. http://forward.com.
"How The Other Half Lives, By Jacob Riis: Chapter 1". Historyonthenet.Com. Accessed 3 May 2017. http://www.historyonthenet.com/authentichistory/1898-1913/2-progressivism/2-riis/chap1.html.
Howe, Irving, and Kenneth Libo. World Of Our Fathers. 1st ed. New York: New York University Press, 2005.
Markel, Howard. Quarantine!: East European Jewish Immigrants And The New York City Epidemics. 1st ed. Baltimore: Johns Hopkins University Press, 1999.
Michels, Tony. A Fire In Their Hearts: Yiddish Socialists In New York. 1st ed. Cambridge, Mass.: Harvard University Press, 2009.
Michels, Tony. ""Speaking To Moyshe'': The Early Socialist Yiddish Press And Its Readers". Jewish History 14, no. 1 (2000): 51-82.
Muraskin, Bennett. "A Short History Of Jews In The American Labor Movement". Jewish Currents. Accessed 3 May 2017. http://jewishcurrents.org/a-short-history-of-jews-in-the-american-labor- movement/#more-41064.
Sachar, Howard. "Jewish Immigrants In The Garment Industry | My Jewish Learning". My Jewish Learning. Accessed 3 May 2017. http://www.myjewishlearning.com/article/jewish-garment- workers/.