NTFS is loosely based on the old V7 UNIX file system. It is not bad, but it does have the ability to be completely blown away. Slightly more volitile than FAT32, but FAT32 has its own set of issues when problems occur.
NTFS can have better security. I say *can* as it defaults to virtually no security.
A converted FAT32 to NTFS filesystem will be sort of a munge between the two and not a full NTFS filesystem. Yes, you can convert an existing FAT32 to NTFS without formatting the partition.