Questions about Woodcessories EcoPad

Yes it is. I use the Samsung Galaxy S9 myself

Yes, the EcoPad is compatible with the Samsung Galaxy S7

You can basically charge any smartphone that supports QI Wireless.

According to the product page on Amazon, the Pixel 3 is also supported. However, it is best to ask the manufacturer directly whether the information is current or correct: https://www.woodcessories.com/ladestation/kabellos/holz

Unfortunately I can't answer the question because I use the EcoPad for my Apple-Natel, which works very well. But I think if the Galaxy Watch supports inductive charging, it should work (don't know the Watch, therefore no guarantee ;-)