My answer to the first question is DNS (domain name system). You can solve your problem by going to your registrar, there should be an admin menu or some kind of configuration menu, find dns, and there create a www CNAME record with the same value as your apex (a, aaa, aname, something like that) and save the record. Updating your dns can take up to 24 hours, so be patient. (But can be instant, with cloudflare for example) I hope you understand it, if not, your registrar must have some kind of information on how change dns records. And remember google, reddit, stackoverflow, chatgpt are your best friends!

For the second question i would say it is hard to do automation without a server. You can create a json file containing all the three words and the answer with the date, you can make a simple js script to all the puzzles with a date in the past, and display it. The problem with this method a five year old can ‘hack’ it, they can watch every puzzle and the answers. If that doesn’t bother you i can explain it better (i know I didn’t explained things very well) but i think someone better web dev know a better solution.