Great. Sounds like your LUN's are correctly provisioned to the host as you can see them in disk manager.
It appears that you are having issues authenticating to the filer from SnapDrive. Make sure your credentials are correct and that you chose the correct transport protocol. You should also verify your permissions on the filer. You can view/change your current transport protocol settings by right clicking the host name in the SnapDrive console and choosing "Transport Protocol Settings"
A way to test your "Transport Protocol" credentials is to walk through the SnapDrive "Create Disk" wizard. You will need to provide the name of a storage system in one of the dialogues you encounter and it will tell you if your credentials are incorrect. At that point, if your credentials are correct, you can cancel out of the "Create Disk" wizard unless you want to continue and create the disk. Otherwise, if your credentials are incorrect, you will need to correct the credentials in the "Transport Protocol Settings" dialogue.
That sounds right...especially if you are using a Windows Domain or Active Directory (via RPC) authentication. You can use a filer local account if using HTTP or HTTPS for filer authentication, CIFS not necessary.
Yes....this is a big concern for me as well. Do a search for the SecureAccess.xml file on the NetApp support site. This file allows you to restrict a host and/or user to specific volumes/luns. Depending on how your IT department is organized, the SecureAccess.xml file may or may not be sufficient.
I was told that the DSM was required for MPIO (multipathing). Version 3.5 of the DSM includes the Windows Host Utilities Kit. I believe you were required to install the DSM and the Windows Host Utilities Kit for versions of the DSM prior to 3.5.
SnapDrive allows for management of LUN's but provides no multipathing funcionality. The DSM is NetApp's ALUA enabled multipathing solution.
With Windows 2008, you may be able to use the native multipathing feature in Windows (without the NetApp DSM). I havent tried this so please share your findings if you decide to go this route. You can verify that it is working correctly by looking in disk manager - if you've provisioined a single LUN and see two disks in Disk Manager then you know the native MPIO stack isnt working. That is a very rudimentary way of verifying MPIO - I dont know of any other ways of verifying proper MPIO with just the native 2008 MPIO feature enabled.
I know the DSM is licensened but I am not sure if it comes for free with all NetApp's. I'd contact support if you have a current support contract.
A note on the 2008 MPIO feature - you may or may not need to do some manual configuration (within the registry I suppose) to get the native windows 2008 MPIO feature to recognize the NetApp LUN's. Again, I havent used it but I can tell you that the native Linux MPIO apparently automatically recognizes the NetApp devices. Again, please share any findings.