Great trip report, and thanks for writing it up in such an honest way! That's how you learn. We all did stupid stuff above our heads when we were younger, and those of us still posting made it out alive, but not everybody did. I advise you to do what I did. Take some of that money you are going to spend on new gear and invest it in getting some in-person instruction from a really well qualified guide. Get a little group together and the cost will be reasonable. or at least find an experienced ice climber who is also a good teacher, buy them a case of beer to take you out somewhere nearby and teach you as much as they can.
Congrats on the probable FA. So I actually want to congratulate you on the decision to rap the route. I don't know the mountain or the descent options, but just going from the TR info, it appears you didn't also. so in my opinion, that was your best decision of the day and just might have saved your life.
if you're not absolutely sure about alternative means of descent, it is ALWAYS better to go back the way you came. Well done. So many climbing accident reports begin with "they decided to seek an easier way down" or "they descended via _______, a route they were not familiar with." You can easily be cliffed out or find yourself in even more of an epic, and once hypothermia sets in, you start making stupid decisions without even realizing it.
Others have commented on your rappel techniques. Trying to save 10 bucks by threading your rope through a wire made my shudder. You were lucky to survive that as well. You DO need to spend more time learning and PRACTICING rappelling in a safe environment. You can read great techniques in books but you need to dial that shit in at home before you try it in the field. (it's by far the most dangerous part of climbing as you probably know intellectually).
If you haven't read through any of the "American climbing accidents" annuals, I highly recommend it. You can learn a lot from the mistakes others make, and it's a guaranteed injury-free activity, as well as being a pretty compelling read.
One last complement- your willingness to keep learning is what will save you. Well done. Lots of people think they're invincible and aren't as self aware as you seem to be. It's great to see.