I'm learning pronunciation and I'm confused with some things. Please tell me how I can differentiate these things:

1. dz,cz,sz,rz,prz
2. o,ó
3. how to pronounce these letters correct: ł , ą , ę

Please confirm, is this "k" in this word silent? "krzesło" . Please share your knowledge, if there is letter before rz, is that word silent as well. I think I saw a word starting with "prz..." 

Just to share what I learned.I learned that there are 2 words for "today" in polish. I learned dziś but I just encountered dzisiaj. Question: Is there any words like this in Polish which have 2 words but just used formally and in everyday speech? 

Just to share what I learned.I learned that there are 2 words for "today" in polish. I learned dziś but I just encountered dzisiaj. Question: Is there any words like this in Polish which have 2 words but just used formally and in everyday speech? 

Why when you ask "Who are you?", you use instrumental for "Who" instead of nominative. Kim jesteś? 

What are the difference between kochać and lubić?