Is there a pattern to when οκτώ (which I entered) is used vs οχτώ, which this seemed to want. My dictionary only lists οκτώ, but that was marked wrong.
Ok, just my view. Context is the key. Here I'd go for "love" not "like".
But for some English expression such as... "I love chocolate." Greek would only use "like"> "μου αρέσει η σοκολάτα/μ 'αρέσει σοκολατα".
I'll ask the team.
This may have already been asked and answered elsewhere, but what's the difference between κοπέλα and κορίτσι? Is κοπέλα more likely to be used for older girls and κορίτσι for younger?
Yes, just as you say usually "κοπέλα" is for older girls. It's also for "girlfriend" as in a romantic way. "κορίτσι" is more general and even for "girlfriend". All depends on context.