I just started with saltwater less than a year ago, and the first fish store I went to I said I wanted to try a 10-gal tank ("nano") and the guy said I should only consider larger sizes because it would be very difficult for me to keep my water chemistry in balance (and also has larger percent temperature fluctuations). The store-owner's words were confirmed by what I also read in a book. I wanted a good book to have from the start.
I don't know how much time per day other people here spend on this hobby, but I think it takes several hours a day devoted to research, taking care of the tank, equipment, food. Personally, it's heartbreaking when one of your creatures dies, and you realize it was your own fault, so I like to put as much time into it as I can.
There's so much science to learn in this hobby: biology, chemistry, engineering, materials science. I wish you the best of luck.