It's a little deeper than "ch" in "chess", you sort of curl your tongue more. I believe I've hear some English dialects/accents pronouncing "ch" the way we do in Ukrainian, but I have no idea which those were. Just listen to the audio a couple of times, you will hear the difference from the "ch" in "chess".
And of course you can pronounce it like "ch" in "chess" and nobody will bat an eye, this sound is normal nowadays...
They change to match the gender/number of the thing that belongs to "whose". чий is for when the thing is masculine singular, чия for when it is feminine singular, чиє for when it is neuter singular, and чиї for when it is a plural thing, of any gender. For example: чий брат? чия сестра? чиє молоко? чиї брати/сестри?
And Ukrainian ones in Southern-Eastern Polish too, for example: SE Polish kapeluch vs. Standard Polish kapelusz vs. Ukrainian капелюх. Also there's a different accent, more like Ukrainian one (and I love it <3 ). Also there are some German/Yddish words, for example: SE Polish durszlak – Standard Polish cedzak - German Durchschlag (I don't speak German, I've found this translation online). My mom's family speaks this dialect, maybe that's why I love Ukrainian and their accent (for me it's cute, not awful, like some others say) :D
My mom's family as well! They're Lemkos from Olchowa, Sanok County. When I was studying formal Ukrainian, I asked my teacher if I could use склеп instead of магазин or крамниця (which is what my family uses) and she said "No, no! Don't use that word!" I'm assuming because it would come across as not Ukrainian to the average native Ukrainian speaker.
That's nice :D My grandma's family is from modern-day W Ukraine, my grandma, my mom and her brother were born in Przemyśl, Poland (both then and now) and my grandad family was from a village called Jasło, but I don't know much about them, but there's a story about Jews in his family and I heard that my mother's family surname is Lemko/Rusyn, so who knows? Yeah, I guess that Ukrainians who don't speak the borderland dialect just don't know this word and might just stare at you with this "what face".