Can I get a list of things that I need to know as a .NET developer?

Apart from knowing the language (c#, vb whatever) well, take a look at the underlying framework. Newcomers omit that part most of the time. Might help with lots of decisions.

- The importance of .Net framework for your program. What happens when you double click on a .Net exe? What happens at the start of a web application? Is the framework is always there or started per app?

- Spend some time with ildasm. Learn what a manifest is. What is it good for. What is Intermediate Language (IL)?

- Difference between reference and value types. Heap and stack.

- What is garbage collection? How the garbage collector is working? IDisposable pattern.

- Why generic classes are important? What was there before them?

- Static vs. instance method calls.

- Passing object references around and keeping a reference (hence preventing GC, especially important for Desktop apps with improper use of events and references)

- For desktop devs: UI thread, background threads, patterns to pass data between these two.

- Basic OO. Virtual methods, overrides, new keyword, interfaces.

- Why strings are immutable?

etc.

I would guess lots. Starting with junior devs and those who just don't care and ending with something like Unity3d scripters.

There is more to it though, like colouring in Visual Studio. I think string must easier on the eye than String

:-)

you'd be surprised how many don't know about it