Beginner switching to Linux – which distro should I choose for game dev + gaming, and how do I replace Windows safely?

I’m a complete beginner to Linux and planning to switch from Windows, but I had a few questions before I make the jump.

What I plan to use my system for:

Game development (planning to use Python and C++)

Coding (Python and C++ mainly)

Gaming (Steam, maybe some AAA titles)

Discord and general daily use

Watching videos / media

I’d ideally like to move fully to Linux for my work in the long run, but for now I’m okay with dual booting while I get used to everything.

My system (in case it matters):

ThinkPad X260

I think my system could benefit from better RAM usage/optimization

My questions:

Which Linux distro would you recommend for my use case?

I’ve heard of Ubuntu, Linux Mint, Arch, Fedora, etc., but I’m not sure what’s best for a beginner who also wants decent gaming and dev support.

What’s the best way to set up dual boot with Windows?

And later on, if I decide to fully switch, how can I safely remove Windows and use only Linux?

How do I safely carry over my data (files, projects, etc.)?

Is it just a matter of copying everything to an external drive before installing Linux, or is there a better way?

Any beginner mistakes I should avoid?

Especially things that could mess up my system or make me regret switching.

If anyone has a step-by-step guide or tips for a smooth transition, I’d really appreciate it. Thanks in advance!