If you are willing to risk a little work, I found Linux Mint as an OS really easy to install and use, and then it will be future-proof (unlike windows) as well as free.

I use Arch, OS is taken care of. Awesome documentation, and I don’t have to care about version upgrades because there’s no such thing. I still don’t know how to properly update Debian. Though Mint has GUI for that, so it’s fine there.
The bootstrap image is also pretty cool. I wanted Arch on a VPS, but I couldn’t boot any installer. I could however use provided Debian rescue environment to download the bootstrap image, chroot into it and use that as an installer. Really cool thing.

Considering that Steam comes pre-installed on Manjaro, that should be fine. Or at least it did when I tried it.

Yeah… I only have mobile data, so that would be a problem. I switch carriers depending on needs, the one with most data is cheap, but is also most overloaded. Depending on location during the day, it can get all the way down to around 0.3Mbps on download.

I tried that once, basically just Google worked.