3) Allow the yogurt to culture for at least 8 hours but likely much longer, I personally find I like the flavor best when it has cultured for 16-24 hours. I like my yogurt tangy. This time may require some trial and error on your part to find what works best for you and your setup.
4) It will still be relatively thin at this point. Once ready, cover tightly and place in the fridge for at least 6 hours. This halts the fermentation, it will thicken as it cools, whether or not you added a thickener, obviously more so, however, if you added a thickener of some kind.