Look for some videos on mixing - it's a pretty big topic. Using decent studio monitors is very helpful. Also, as you mix, compare your sound to some reference tracks that you like the sound of

It wouldn't have any signal on it's own. I believe it's a resistor and the amount of resistance changes with temperature. You could run a weak signal through it and then amplify that. The sound would be affected by temperature, although I dunno if it would be enough to add any interest

I don't know what it's like to want to do these things while having no idea where to start, but I can recommend that you experiment with things that you don't really care about because you might end up finding something new and interesting to care about.

I made a mix in a free sound editor for fun because I liked learning different software. I accidentally took an interesting pic with a p&S camera because I like reading manuals and wanted to see how the macro switch worked.

I have absolutely watched some Cricut and Glowforge videos. One of them could find a home here one day

Yep - learning CAD is the way to really get the best value out of your printer. Sometimes you save a few dollars by printing, but the best is when you print something that you didn't even have the option of buying.
(Clearly I prefer functional prints 😀)

Oof! I was wondering if I should set up an account and post music there. I guess this answers my question

Anything N. K. Jemisin wrote

Is this quieter than the MK3s?

"Back in my day" when I released my last album, CDBaby was the only major option for self publishing. There's so much to learn about all the options that are out there now.