Is Online PIC Compiler completely free?

I don’t know assembly language and it is the first time I open this program, what should I do?

What are the differences between Online PIC Compiler and other PIC assembly compilers? What are the cons and pros?

I’ve written/found a program that should surely work, but Online PIC Compiler is giving errors/not working properly. What can be the reason?

How can I help/support Online PIC Compiler?

What can I do with assembly language? I think it is very primitive.