здравствуйте и до свидания are more formal while привет и пока are less
I'm pretty sure that would translate to the more formal "Good bye." Whereas Пока just means bye. I mean, yeah, you can use both, just one is more formal.
The accent in a syllable changes the sounds of most Russian vowels. Хорошо, which reads as if it would be sounded: ho-ro-sho... actually reads like: hah-ro-sho, because the first o is in the accented syllable. I think the first class, Basics, discussed the vowels and accentuation a bit, but this class in general doesn't seem to cover the topic with a lot of detail.