There is no such thing as average database size or average disk usage, it depends entirely on how much data is stored in the database (ie how many pages and articles, blog posts etc etc as well as how large the content is) and how many and how large files are uploaded by users to disk storage.

A new installation of mojoPortal with all features and files is about 80-90MB on disk, see the FAQ if you want to find some files to prune to reduce disk space a little.

In general disk space is cheap and should not be a concern for any important web site.

Best,

Joe

you can safely delete skins you are not using. You should probably keep the printerfriendly skin or else remove the printer friendly link from your layout.master file of your main skin.

Hope it helps,

Joe