Is it still useful to load the lmodern package?

There are so many fonts similar to Computer Modern (CM) now, a FAQ like the TeX FAQ might be valuable. Pending that, the answers to your two questions might be

1. yes,
2. Type 1 (T1) or OpenType (OTF) access to a moderate set of CM-like glyphs, without going into the extremely large cm-super set.

For what it's worth, I use the lmodern package for most of my documents. One day I'll graduate to something more exotic...

Well, none of the two most common LaTeX distributions use Latin Modern by default, they still keep Computer Modern (as of November 2013). So yes, calling \usepackage{lmodern} is still advised, unless you find cm-super (which is another fork of Computer Modern fonts) more convenient.