RE: Oldest RC Company
Oldest RC is hard to say, since it didn't really start until the late 40's / early 50's. Many of the companies that produced RC goods started out as free flight or control line suppliers.
As far as oldest model airplane company, that would be either Cleveland or Guillows, both say they started in 1926.
Goldberg got bought by Lanier, which in turn was bought by Hobbico/Great Planes/Tower - I truly hope they treat that name with the respect it deserves.
Comet was started in 1929 and their designs were bought by Guillows in the late 90's.