The shapes of the letters themselves aren't copyrightable in the US, so that if you vector-traced them perfectly, using your own "control points", you could distribute – and in fact, would hold copyright in – the resulting font file.
When discussing copyright "font" doesn't refer to the shapes of the letters (which comprise a "typeface") but the programmatic implementation of that typeface, which has been held to involve independent creativity. So if you take an existing vector font file, and alter the control points, you've created a derived work.
The situation is different in many other countries, which do allow for a copyright in a typeface. Generally the term of copyright is much less for a typeface than for many other works.
