Also, Google has datacenters all over the world, meaning that you will be able to play on Stadia using servers in your country. That will be a huge help in decreasing latency. With a nearby server you can get something like 8ms ping or less on a good connection, even the encoding latency is higher than that.
I used it on my gaming laptop, but it shouldn't really matter what you use as long as the Nvidia software supports hardware decoding on all 3 platforms (Nvidia/AMD/Intel), which I'm not sure if it actually does. But it's just a beta, so that's something they will hopefully sort out before release.