I should think you've already bumped into at least two cases, nominative and partitive (in singular). :) Can't remember if they've introduced genitive, inessive and adessive yet at this stage.
Nominative: kahvi, koira, nimi, minä
Partitive: kahvia, koiraa, nimeä, minua
(Genitive: kahvin, koiran, nimen, minun)
(Inessive: kahvissa, koirassa, nimessä, minussa)
(Adessive: kahvilla, koiralla, nimellä, minulla)
Language difficulty depends on your native language, so for English speakers, Romance and German languages take about 600 hours of dedicated study, Arabic and Hindi are further away, so they take about 1200 hours, and Japanese and Chinese are even further away so they take around 2200 hours. And it works in reverse as well, i.e., English is one of the most difficult languages to learn when your native language is Japanese.
I was told that being Hungarian makes it easier to learn it. Probably works for Estonians too. So pro tip #1: be Hungarian or Estonian. From there on, smooth sailing... :P (nope):D but I'm actually experimenting this year to see if I can make it to B2 by this Christmas :)