In your description, you are mixing the two different permission sets, and I'd like to inquire as to why?  All files and folders on the cluster have a Unix-style permission set - RWX set for 3 different groups of users, the owner, the owner's group, and everyone.  These can also be represented as a number and set as such.  For instance the Read and Execute permissions would be 0555 - resulting in dr-xr-xr-x for a directory.  Then the files would be set to 0444 for -r--r--r-- permissions.  That would be the POSIX permission set and OneFS would then translate this with simulated ACLs for any SMB connections looking for access to these files.   Now you are doing the chmod +a command to specify an AD group and set ACLs explicitly on the directory and files.  The default behavior as you describe is that setting a directory permissions automatically sets all of the files within that directory to the same set.  The resulting POSIX indications are what you are looking for, but they are generated based on your ACL selection.   Therefore - if all you are concerned about is the POSIX settings - NFS users, or are simply trying to script this action for other directories... you can use a series of chmod commands to specify these permissions.  You would specifiy the directory permissions first, then a chmod command would have to be run on all the files within that directory to remove the execute permissions from those files.   If you are specifically looking for the ACLs you specified in an SMB environment - you could browse to that folder from a Windows client with access rights to the permissions and right click the folder, set the permissions from the properties window.  Then get properties on the files within the folder and from the properties window on those files, remove the execute permission.  This should result in the same thing.  If you try this method, you can go back into the folder from an SSH connection to the cluster and use "ls -la" to see the resulting permissions of the files. 
Any idea how do I set permissions for "other" as r-x on folders and r-- for files inside a folder "Testfolder1" in Unix ? This is a special requirement from the business.  I have set permissions like this "chmod +a everyone allow dir_gen_read,dir_gen_execute,object_inherit,container_inherit Testfolder1" and it correctly sets the permissions r-x for folders for position "others" but files also getting r-x permissions. For only files, how to set the permissions to be at r--  ?
Isilon folder permissions