Nautical Flags:
Possibly Baby and the Battleship or Potemkin. Both of these are in the Public Domain.
Newspaper Presses:
Probably in the 1931 version of The Front Page or in Nothing Sacred. Both of these are Public Domain.
Seance:
Meeting at Midnight, a Charlie Chan movie which is in the Public Domain.
Some episodes of the old TV series One Step Beyond are on tape, and are copyright-free. The episode about the sinking of the HMS Hood, and prophetic events which supposedly preceded it, includes a scene where people are spelling out a message using anagram tiles and an inverted tumbler. There is a scene like this in the old Ray Milland film The Uninvited too.
Mail plane:
In the Public Domain movie Made for Each Other with Jimmy Stewart and Carole Lombard there is a great sequence with a pilot in a one seat open cockpit plane who is rushing to deliver medical serum.
Roman Messenger:
The David Bradley production of Julius Caesar, circa 1950, with Charlton Heston as Marc Antony. This is in the Public Domain.
Neon Signs:
Detour, which is in the Public Domain, or the original version of The Postman Always Rings Twice, which isn’t.
Telegraph:
Western Union. I believe there is also some good telegraph stuff in Gunga Din.
Early Television:
There are a number of video compilations available of old Popular Science newsreels. One includes a segment about the “amazing advances” made in television in recent years–this is from about 1940. There was also a segment (possibly on the same tape) about Hugo Farnsworth and his experimental studio. There is also an early Bela Lugosi thriller, Murder by Television. All of this is Public Domain.
Alternatively, you could try the movie Avalon, where there is a funny sequence in which a family, circa 1948, sees TV for the first time. In The Ziegfeld Follies, Red Skelton does a sketch as a man trying to do a live TV commercial for gin. This was later imitated as the classic “Vita-Meata-Vegamin” bit on I Love Lucy.
Also of interest is a scene in the the movie serial The Shadow where distinguished guests are invited to a TV demonstration. Woman: “But I thought television was still in the experimental phase”. Man: “Oh no: there’s been remarkable progress in recent years”.
Gossiping:
There is a good silent sequence in The Boy with Green Hair as a message is passed from one person to another. They are not all women.
Candlestick phone:
Citizen Kane, and the coming attractions trailer for Citizen Kane. I’m not sure: the latter may not be under copyright.
Angel and Devil:
Animal House.
Lights Dimming:
I’m not sure, but you might want to check the execution scene just before the end of Angels with Dirty Faces.