Good evening,
Check that your iPhone is "wireless charging" compatible.
If it is, put your phone flat on the "wave" symbol and the charge should start after 2 to 4 seconds.
Good evening to you.
I found the answer myself some time ago: No, you cannot charge the Smartwatch.
According to support from "Walter Walet", the following page is used to check which devices support suitable wireless charging: https://www.mobilefun.co.uk/blog/wireless-charging-guide/
To your first question: The dock fits even a Galaxy Note. There should be enough space for the S9.
To your second question: Everything is complete and can be used directly.
Have a nice day
Unfortunately, no, this will only be supported by Apple's airpower. This will (hopefully) be released this year and you will then be able to charge an iPhone (which is QI capable), an Apple Watch S3 and the new Airpods at the same time. Otherwise just google "Airpower", I hope it helps.