Yeah the things that you have said they do really matters a lot.
As this a global platform so time zone is different and it is you that needs to decide when your followers will be online and that is when you can connect with them
As for the short and long posts it totally depends on you because you know what you are capable of and interaction is what matters and one other thing that I do believe is that people only like those posts where they can learn sth or sth interesting or sharing your thoughts with others and many other things which you will get to understand if you get to spend time in here.
About tag , yes they are really important as this tags decide what your posts are about and those tags will attract that kind of followers towards you.
All in this you can say a small research can be done by a Steemit user :)
I hope it answers few of your doubts/ questions .