Sorry, Partition Image is not a high level program, as Ghost. Ghost makes a file copy, and we obtain a file near a tar.gz archive, with other details (as the boot sector). But PI works in a low level, as Drive Image: it copy used blocks of the disk. Then, it doesn't know where files are written, and cannot allow to see files in the image without restoring.
The current version can only read/write from/to a partition. PI doesn't use the partition table at all. (The linux kernel read it, and PI can directly use hda1, hda2, ...). But I d'like to implement this in the future, to allow users to select partition to save/restore from a list (with name, size, filesys, usage, ...), and PI would be able to create the partition if need at restore, or resize it...
You can't restore to a smaller partition (you will have an error), but it's possible to restore to a lager one. In this case, some space will be lost (I suppose the OS cannot use all the size). PI don't have a resize feature. I d'like to add this in the future too. It will allow to restore into a smaller or larger partition. In deed, PI is low level. It uses data blocks. Then resizing is possible, but that's a complex feature to implement. With some File Systems made to be easily resizable (as NTFS, ext2, ReiserFS), it may be easy, but with FAT, it's hard to do. For example, when resizing from 1,5 GB to 3 GB, you must change FAT16 into FAT32... You can use GNU Parted to do it.