Does the WInMain function is mandatory ?

[Vinod K Chandran via Digitalmars-d-learn]

Hi,
I would like to do some win api coding in D. I just taste the 
syntactic sugar but cant do anything more. I have few questions.
1. Does WinMain is needed for a D program in order to use win api 
?
2. Can we use D strings in win api functions ?, If not, please 
show me how to convert strings