1. I checked some materials, and noticed that in the 1830's-1870's (Basically after the Decembrist Revolt and before the Ems and Vałujev declarations that banned much of Ruthenian book publishing), "Ruthenian", "Ukrainian" and "Malorussian" were used interchangeably. A good example is "Русалка Днѣстровая" a Ruthenian almanach (with some Serb poems as well) published in the 1830's in Galicia, in which even the three authors, which were called "The Ruthenian Triad" couldn't make up their minds on whether Ruthenians were a separate nation or not. I feel like this is a result of general political, lifestyle, geographic and demographic factors preventing both Ruthenian groups from developing a separate identity earlier, they much more cared about having a good harvest and whatnot than national politics. Galicia is deemed the "Ukrainian Piedmont" by nationalists because it had more access to high level education and western European culture which made the national revival go faster there.
2.Jews and Greeks were a major part of Odesa's population up until WW2, which sets the population percentages similar to that of Lviv/Lwów in the same time period - 60% Ethnic full Russians or Poles, around 20-30% Jews and the rest being Ruthenians and other ethnicities. 3.Fair enough for a russophile, but I have one problem: Belarusians didn't separate because of not wanting to associate with their southern brothers, in fact the nationalist movements of Ukraine and Belarus co-operated closely in the late 19th and early 20th centuries (For Example in 1917-1918 Ukraine and Belarus formed an alliance which saved Belarus from a famine, and in WW2 ultranationalist paramilitaries co-operated closely).
I would also like to add that I am kind of non-ambivalent towards Ukraine partition plans not because I hate my country or want a partition to happen, but because realistically it could happen easily. These is simply little cultural unity between the various regions. Throughout the 19th and 20th centuries national revival figures from all of these regions had very different views on what Ukraine should look like both borders-wise and politics-wise. Any sort of national unity began dying during the War of Independence (I.E. the WUPR allegedly tried to orchestrate a coup in the UPR to put general Petro Bołbočan in charge, WUPR leadership openly was sceptical of the UPR leaderdship, all the while Petlura began negotiations with Poland a mere few days after the Union Act). This conflict alone showed that a united Ukraine is fairly hard to achieve because of varying political interests in the different regions. Even nowadays "Zapadenci" and "Schidniaky" have basically the same, at least cold, opinion on one another. A nation where a person from one part of the country calls out his fellow citizen for language while the fellow citizen in question considers the other an uneducated villager can't stand.
TL;DR: I am a doomer about Ukraine's identity just like I am a doomer about everything else.