The writer can choose the sentence ending style they want, usually between the -다 and -ㅂ니다 form (-아/어요 and -아/어 are too informal for non-personal writings like an essay or news report). The common practice is to use the succinct and to-the-point -다 ending except for when expressing soft and warm thoughts or when writing for children. Your example seems to fall in this "soft" category, so I would say you can go either way. For the verbs other than sentence endings, it is most common to use neutral forms without honorific suffixes. This is because the purpose of most writing is to present thoughts and information which is independent of social setting, and secondly because you cannot easily assume the age of the readers so you can target the language to them. The safe practice is therefore to use the neutral forms, but again, writings intended for children can be different. In your example, some verbs come without the subject, suggesting they are about people young and old. This is another reason not to raise or lower the verbs. I would right it this way. - *개롤을 들*어면서 음식을 함께 드십니다 -> 캐롤을 들으면서 음식을 함께 먹는다/먹습니다. - 저녁에는 선물을 주고받고 어른들은 따뜻한 와인을 마시기도 한다/합니다.