bring your spices to Poland, otherwise you would have to look for some all over Warsaw - I just find that it is easier this way and since they don't weight that much you might as well bring a handy supply.
So, anyway, food markets?
you should be OK in Warsaw when it comes to fruits, veggies, meat and so on. If you avoid processed products, you should be fine.
Last one: Baking. China didn't have ovens
they are ovens in Polish kitchens, so you should be fine.
and what dairy (milk, but not eggs, I'm fine with eggs) substitutes I may need to plan ahead for.
what are the milk substitutes in baking. I bake at times and I don't recall using milk products while baking. Perhaps you have a particular dish in mind?