Waiting for someone else step in and provide a complete answer there, when such answers already exist, but in different posts seems unlikely, besides a little bit counterproductive.
Alternatively, you can accept the answer to your main question, i.e., the question number 1, which is more closely tied with the question's title and; simultaneously edit that accepted answer (or leave a comment beneath it) to include a final sentence in it along the lines:
Edit from @Ytsen de Boer (OP): question number 2 is [satisfactorily] answered at @xxx user.
This way, you can accept one answer and promote upvotes on both answers. Everybody wins.
- Accept one of both? A: Yes, but make sure to be clear the other answer, answered the second part of the question.
- Have posted 2 questions in 2 posts? A: Yes, if you had not posted it yet.
- Answer the question myself, borrowing from, and mentioning, the other authors? A: This is not productive to me; it would compete with the original answers, removing attention/credit/votes from them. If such answers were posted as comments, then, yes.
- Ask the authors of both answers to include their answer to the other question also? A: No, if they did not answer the other part of the question, it is because they did not want to. Not that asking would hurt, but why ignoring the complementary existing answers?.
- Do nothing? A: Given the amount of answers received, doing nothing would be quite frustrating.
- Wait for someone to answer both questions in a single answer? A: Not productive.
- Do something else? A: Not necessary, option 1 is fine.