First, read this: Grimes - How to Make Music for (almost) Free

I personally prefer Garageband to Ableton - Ableton is still good, but maybe makes more sense for electronic music. Ableton Lite comes free with some midi controllers, like the Aturia Minilab. This is perfect if you don't have a Mac. It'll be about $60.

As for mixers - you can also buy a mixer that can act as an interface, like the Yamaha MG10-XU. Having a mixer is useful bc you can also use it for live performances, and plug your monitors (speakers) directly into it. However you can't (always) plug a guitar or bass directly into a mixer - that requires a preamp (because the signal it sends out is so quiet). Most people use the Scarlett focusrite 2i2 as an interface because it has a built-in preamp.

You can actually record sound just fine on an iphone's built-in mic, it's actually better at picking up lower frequencies than most dynamic mics.

Recommended gear:
➺ Computer
➺ Mic (Good brand: Shure SM-58)
➺ Interface (Good brand: Scarlett focusrite 2i2)
➺ Headphones (Good brand: Audio Technica ATHM50)
➺ XLR Cables for connecting the Mic/speakers
➺ 1/4 inch (instrument) cables for connecting instruments
(buy nice cables, they will last longer)
➺ Instruments!
➺ Bonus: mixer (Good brand: Yamaha MG10-XU)
➺ Bonus: speakers/monitors (Good brand: KRK Rokit)

None of this stuff is 100% necessary (except maybe a computer), but if you have all of the above you can make, beautiful, studio-quality music. Everything else can be learned through Youtube tutorials. Good luck! :)