If you want to learn Linux, install Gentoo. That’ll give you a pretty good understanding of what’s going on. It’ll be an intense process though.

If you just want to install and use Linux, pick one of the usual suspects: Mint, Fedora, openSUSE Leap/Slowroll, whatever. If you come from Windows, picking KDE Plasma as your desktop environment (DE) is a good choice. Mint’s Cinnamon should be good too. Picking a popular distro usually means troubleshooting is easier, since someone else out there most likely has the same issue you have, and documentation is more comprehensive.

Remember that many distros provide a live environment you can run from a USB stick. Try a couple with different DEs and see what fits your needs. Honestly, the distro doesn’t matter that much, they all do the same thing, more or less. Maybe try to pick your DE first and then just go from there.

If you want a simple answer, pick Mint.

Posteo is affordable and, at least to my liking, private enough.

Ever since VLC came on the scene it has been my go-to. Just a really functional player that plays almost anything I throw at it, and I like the UI well enough. For now I have no reason to use anything else. I’m not hating on other players, but VLC works for me.