What advantages of .net from visual lisp
dotNET provides much more capabilies than LISP, including a large number of standardized tools through the dotNET Framework that are otherwise unavailable in LISP. That includes win forms and WPF for user interface. With this capability comes a lot more responsibility for proper planning, knowledge of language and AutoCAD, error handling, and following good coding procedures. LISP can be made to work with hack'n'slash machete coding; dotNET will fail or tell you "I can't do that Dave".
If you are going to fly by the seat of your pants, expect friction burns.
"I don't know" is the beginning of knowledge, not the end.
Managed dotNET before unmanaged dotNET (ARX). C# is far, far easier to pick up for those who don't have an extensive background in programming. However, if the intent is to develop and support full-fledged ARX applications its probably better to stop looking at AutoCAD, develop skills in C++.NET, and *then* get to work on the ARX development.
If you are going to fly by the seat of your pants, expect friction burns.
"I don't know" is the beginning of knowledge, not the end.