FontLab (commercial app) can import Illustrator paths: http://www.fontlab.com/contact-and-support/faq/faq-fontlab-typetool-mdash-glyph-drawing/ . FontForge (FOSS) can as well, and apparently some other vector formats: http://fontforge.org/importexample.html
As for the second part of your question: most professionals use tools such as FontLab, Glyphs, RoboFont, etc. and draw directly in the font-making applications. In many cases they will work from a template/background of some sort, such as a scan of hand-drawings, or perhaps outlines of a different weight of the same design, etc.