If 'se' means 'and', then what's the difference between 'se' and lengthening and stressing the last vowel?
Well, the words in this example aren't nouns as in the previous exercise so maybe "and" (se) is exclusive to mult. phrases or verbs. (disclaimer-- I know nothing)
Yes, my impression was that the stress is used for lists. You don't say se between words in a list.
Japanese has two different ways to say "and". For multiple nouns, they use a separate word just the way we do in English. For multiple verbs, they conjugate the non-final verbs a particular way.
I imagine DJP took inspiration from Japanese, but flipped around where to apply which technique. Multiple nouns are declined a particular way. "Thank you" and "hello" are not nouns but pleasantries, therefore declension does not apply to them and a different technique must be used.
Do kirimvose and rytsas consist of multiple morphemes? How can they be analysed?
According to the Dothraki Wiki, kirimvose is the instructive of kirimves, meaning happiness, which again comes from the word kirine (which I am sure you know by now), and the derivational suffix -ves, which turns adjectives into abstract nouns, much like the English -ness. Rytsas comes from the word rytsa, meaning healthy.
My interpretation of this is that lengthening the vowel only applies to adjectives, nouns and descriptive words. "Se", I presume, is used for any other instances other than a list.
I'd like to think this is how HVers usually greet one another. I don't know of any other languages that thank people immediately, unless it's "Thanks for coming. Thanks for choosing Brandname. What can we do for you today?" I can now do customer service in HV! "So why were you fired from the call center?" "Um, it's a long story."
That's not the point. Duolingo is not teaching us handy useful phrases. It's only teaching us grammar and vocabulary. So there will be odd sentences, but what they mean isn't important and whether anyone would really that isn't really important.