There are many resources to explain inodes in detail. Let me try to give you a basic understanding.
First, inodes are on disk descriptions of the storage allocation of a file in a filesystem. It does not contain the filename used to access the storage. It does contain the number of path names that refer to that storage.
Second, when a file is opened, a vnode is created that contains information from the inode. The OS only uses the vnode during file access.
Third, a file is located via it's directory entry. A directory entry basically consists of a file name and inode number. So when you open a file, the system searches for the directory containing the file entry. It then uses the inode entry to create a vnode.
Fourth... This size of the inode is not really useful. It does not determine file size. It only contains information that describes the information necessary to manage the file.
Fifth... the -i option of newfs refers to the density of inodes. That is.. how many inodes will be created. It is actually a mkfs option.
try this:
22.]System Administration Guide: Devices and File Systems - Sun Microsystems