(Ja) mam=I have
ty masz=you have(one person)
On/Ona/ono ma= he/she/it has
My mamy=we have
Wy macie = you (guys) have
oni/one mają= they have
I almost replied to you with "tusen takk." The Bokmål is taking over my brain lmao
You can use "ja" if you want to, sometimes you just feel like it is important that "YOU" have milk and bread. But you can omit it, it may not be something to pay any attention to. But "mam mleko i chleb" should be accepted.
You cannot say "a bread" as far as I know, it has to be "a loaf of bread".
"some" technically means "trochę" (trochę mleka, trochę chleba) but I guess it's acceptable here. Added.
There is no separate alphabet skill as these are just diacritics, special characters. You learn the pronunciation while doing the course.
"ę" is nasalized "e". It's like Spanish for "Euro".
"ą" is nasalized "o". It's more or less like the vowel in "rose".
"ł" is like "w" in English. While Polish "w" is like English "v".