This and this can help. But basically:
1) IIS now uses WAS
2) IIS hosting. Pros: usually hosting code is not required, easy to maintain, IIS infrastructure (security, sessions, site integration, etc.). Cons: Passive services require IIS.
3) . : . : , req. -, ( ).
4) Windows. : "", , (//, () , , mmc ..), . : req. -, (vs IIS-).