I can't really point you toward anything as I'm not in a position to do so -- but I can offer my general advice:
Not that I know C# at a professional level, but I simply suggest that you get a copy of the documentation, specification, and read that stuff.
That's how I learned to program: inhaling manuals and error and trial.
Once I got a language under my belt, the error and trial became trial and error, and reading documentation became bearable.
I've never used C# professionally, as I've said, but AFAIK it's not a really difficult language.
A lot of the concepts you've mentioned are very simple -- delegates are essentially member function pointers bound with a class pointer as the first argument, or that's at least how I think (in terms of C++)
And the JSON spec is a massive fourteen (or 17?) pages long (yeah, I remember that), and is mostly pictures :)
Once again, all of this stuff you should be able to learn to an acceptable level within a few weeks at max. It doesn't matter to the company that you don't already know this stuff, because it's not massively difficult to learn -- as long as you learn it within a reasonable time-frame, there should not be any issue You were hired because the company believes you're better then the rest of the applicants, remember that.
Start by figuring out JSON. Work through it and you'll get it faster than you would expect; don't panic or get stressed, just read the stuff, and use it a touch, so you actually apply it.
Hopefully you didn't take the job for cash.
You won't have fun.
If you do enjoy yourself, maybe you'll realize that MVC is actually a really versatile and elegant design, if it's not a bit overkill for small projects.
Good luck!