Is it acceptable to use the likes of 진짜, 정말 and 아주 when describing someone?
Yes, although I don't think 아주 is as natural sounding. I just avoid saying 아주. My boyfriend, who is Korean, said it's not used in spoken Korean very much. But 진짜 여쁘다 makes perfect sense :) 너무 can be a fun exaggeration too. She's too pretty.
Both quite and very are accepted. Surely very is a stronger word than quite, but there's no rule that defines how pretty is very pretty or how pretty is quite pretty. The Korean language also has various adverbs for emphasis which only differ in degree, but I don't think there's one-to-one correspondence between Korean and English, thus we accept both. Just like English, such words are often interchangeable, so please don't memorise words like "This word means very and that word means quite"
because it doesn't say that girl/woman, that would be 그 여자아이/여자
그녀 is the word used for "she"