How can I Filter the data ?
You can use One-key shortcut, use Context menu, or Edit the filter manually.
How can I calculate the frequency of a variable?
From anywhere within that variable's column, right click and choose “Frequency” from the context menu.
How can I apply a library filter to all the datasets in a folder?
Right click on the variable's value, then choose the WHERE clause from the context menu.
I use StatDataViewer to view the SAS dataset every day. It is a real helper tool.