1. Where is the Microphone Capsule?
I know your excited to get to recording, but when you are using a mic for a live source, make sure you know where the front of the microphone capsule is located. Different mics have different locations.
The SM57 is a front address microphone. To point the source at the front of the the mic
Where a side address microphone, like the Audio-Technica AT2020, you point the source at the side.
2. Less expensive vs. more expensive audio cable: Does it matter?
Short answer, no. I'm not saying buy the $2, twenty foot mic cables from some country you haven't heard of (unless it gives a cool sound, lol), but most mic cables you see at your local music store will be great. I made my own (I'll do a blog on making your own cable at a different time) and 20 years later, I'm still using them.
3. Mixing your own recordings
If you have the willingness to take the time to learn that DAW (digital audio workstation), watch hours and hours and hours of tutorials, listen to really bad mixes you've done over and over and over again - on multiple speaker sources, get critiques from strangers on Facebook, Reddit, Instagram, ad other social media spaces, have ups and downs, frustrations and sparks of hopes, for at least a year. Then, as a famous shoe company says, "Just Do It!" All the more power to you on your goal to being a mixing engineer. You can do it if you put the time into it. If you're not the type to put all your time into it, find someone you know or reach out to some mixing/recording engineers and have them mix it for you. I am not trying to discourage you, just want to give you a real life look into your possible future.
4. Amp Simulators
Amp simulators are great. So are tube and solid state amps. Custom amps are another great path. The technology is getting better for all of these. Find one that matches your instrument the best and learn it the best you can. Are you the kind of person that likes to adjust every little thing or just plug in and play? These are all great questions, but only you can answer. If you walk into a recording studio and the engineer says that your amp just won't record well and he has a better amp for you to use, or a simulator will work just as good, that's fine - they have their own opinion and knows what works at their studio. But it doesn't mean it's the right answer for your sound. Just say something like, "Yeah, I'll definitely give it a try IF my own setup isn't translated the way I want it to sound.