My *guess* is that you'll get more help with the legacy build system (including Makefile.win) in the ApacheLounge forum at http://www.apachelounge.com/viewforum.php?f=6 (ApacheLounge is not affiliated with the ASF; it is a Windows-centric community around Apache httpd.)
I suggest trying the newer cmake-based build, which directly supports more levels of Visual Studio using either nmake or Visual Studio project files; see http://httpd.apache.org/docs/2.4/platform/win_compiling.html#cmake You'll probably get the most help for that here.