I landed on Mint because it's a simple no fuss distro that feels familiar to Windows refugees. I game on it just fine and use my computer for a lot of things so wanted something general. I bounced off Ubuntu because it has some decisions that are trying to protect you from actually learning Linux, which is a priority to me.
As a professional spreadsheet pusher, I can confidently say that LibreOffice (the Linux version of MS Office) has been able to do everything I needed that word/excel can, and then some.
But really any distro will be able to install the software you need, and it's easy to switch. Just try it and have fun.
Internet: I've used teksavvy in the past and had a good experience. It's not independent infrastructure (nothing is) Mobile: freedom (formerly wind) has it's own network. It was acquired so isn't quite the scrappy underdog standing up to oligopoly it used to be, but it still seems like the best option. My phone prices have actually gone down over time with them