Well, I'd like to give two proposals regarding Poland and Czechoslovakia. Incorporating them into Russia wouldn't seem a good idea. Poles in Galicia enjoyed a wide array of privelidges - in case of Galician incorporation, you'd have to either extend them to the Congress Kingdom, or restrict them. Both results would be dangerous - first may lead to further liberalisation of the Empire (remember the Bolsheviks are still lurking out there... And remember Alexander II's fate), the second would result in further antagonisation of the Polish population, which in turn may result in open insurrection.
My proposition on the Polish question; release Poland as a puppet kingdom, with Nicholas II crowned as the King of Poland - just like Alexander I did after the Congress of Vienna. Such state should include not only Congress Poland and Galicia, but also Poznan, Bydgoszcz, Katowice, Gleiwitz, Oppeln, Gdynia (which is ahistorical in this scenario - before 1920s the biggest city in there was
Władysławowo, not Gdynia), Allenstein and Torun - provinces with high percentage of Polish population. I guess Gdansk would have to remain a Free City, since I believe the Entente would press on such resolution. The Prime Minister of Poland in such case should be
Roman Dmowski - IRL he initially supported cooperation with Russia, but when it became apparent Russia has no chance against Germany, he reverted to France, which is not a case in this AAR.
As for Czechoslovakia - I'm not sure if tsarist Russia would be happy to see an ancient Hungarian state being dissolved in favour of a republican Czechoslovakia. Rather, I guess a triumphant Russia would push towards an allied Hungarian Kingdom, stripped of Transylvania, but with Slovakia still in its borders. I'd propose
Michael Alexandrovich, Nicholas II's younger brother as the Hugarian king.
And one last thing - the Ottomans. Go for incorporation of whole historical Armenia and occupation of the Straits. Bulgaria could be punished as well - for example, by a behind-the-scenes coup d'etat that would put a Russian-backed tsar on the throne. My candidates would be either one of Ferdinand's sons, or Russian grand duke
Cyril Vladimirovich, Alexander II's grandson and the 3rd person in the Russian line of succession.