As far as too long or too short, I say don't waste viewers time. Some YouTubers stretch their content to try to boost view time, but this is a bad idea. Viewers will either skip ahead to try to get to the good stuff, or they will give up and move on. I don't worry at all about a video being too short. If you can say what you need to say in a minute, awesome. It won't generate huge view time, but audience retention will tend to be higher.
Agree that having unique keywords will make your video stand out, but it won't help you with the algorithm unless potential viewers are searching that keyword. Also, agree that keywords should be both stated in the video (that is auto-captioned) and written in the description. I would add the tag as well. Find synonyms for your key words as well.
Captivating titles and thumbnails will help click-through rate, and that will help everything else. Just make sure that you deliver on what your titles and thumbnails promise, else it's just clickbait.