I hope this doesn’t come over as condescending.
First off, nothing is set in stone, your grow is as individual as you are. Even if your neighbour had the same identical gear and set up it would be different, with the way you water, feed, soil mix, house temps. You will never get a straight answer or an answer that is perfect for your situation, because of this.
Everyone’s answer’s will vary to their personal growing experience with their environment and set up. Everything you will be told is a generalization of experience, that will not fit your circumstances exactly but it will get you in the ball park where you need to be.
Growing weed is not an exact science unless you grow in a laboratory
So when you read something that says something like seedlings like best 80F and 60% humidity, that’s correct for the majority, but it doesn’t mean any temp or humidity, other than that is wrong, the plant will survive and grow, but just a bit slower than optimal.
I understand where you are coming from, your excited and want to do it right, I was exactly the same when I started, but dont panic if its not perfect, you will get there. Most of the fun is in the journey not the destination.
Yes and Yes, you dont want the small fan blowing directly at them mostly over the top.
I try and avoid anything that uses a lot of electricity lol. My plants do well in any humidity so long as my temps are around 75F some times they will need more water sometimes they need less. My flower room is currently at 80F with 18% humidity, not ideal, but they are doing well. Out of the 2, I would go for the basic humidifier, as it sounds more adjustable.