What context is this in? Do you just have a *-flat.vmdk file that you're trying to work with? To get info such as provisioning, format, and size, check the vmware.log files for the corresponding VM, the info should be in there. A 2nd option is to make a copy of the .vmdk (not the -flat.vmdk) and open it in a text editor like Notepad, the virtual disk info should be in there, too.
As for the guest OS drive letter, there's really no way to tell (at least that I know of) without starting up the VM itself. The hypervisor doesn't care how the guest uses the virtual disk, it just manages the virtualization aspect to present the vmdk as a physical disk to the guest.
Hope this helps!