Hello, this is my first post so I decided to start with an introduction. I'm new to calculator programming and graphing calculators in general - I just bought my first calculator, a TI-84+, a few days ago. However, I quickly became interested in making some games for it. That's how I discovered Omnimaga. I have some experience with BASIC (computer BASIC, not TI), and a bit of experience with a few scripting languages (like C# and AS3), however I would still consider myself somewhat of a novice when it comes to programming. After looking over some posts on this forum, I have a few questions I hope someone can answer:

1) I've been reading a lot about shells for calculators, like MirageOS. What exactly do they do, and are they necessary? And if so, which one is most recommended?

2) As mentioned, I'm interested in learning to program my Ti-84+. Where exactly should I begin? I know there is Ti-Basic, Axe, and ASM, and I'm interested in learning ASM, but I know I should start with Basic or Axe. Which one would do you guys think I should begin with? I have some BASIC experience, if that would help. Also, what is the best tutorial/learning resource for the language advised?

I know this probably seems like a lot of questions, but like I said, I'm new to all of this, so I can't help being curious 

Thanks in advance.