Percussionist's Pleasure

Answer 4 is not entirely untrue, but apart from the whistle he uses purely conventional orchestral resources to create his effects, as with many other subsequent 'train' pieces (e.g. Vivian Ellis' Coronation Scot and Arthur Honneger's Pacific 231).
Answer 2 remains hauntingly true, but it is not easy (even if you are determined) to find out how the effect is supposed to be produced, whether by the percussion section in the stage pit or by the backstage department

Spike Jones and his City Clickers were famous for their quickfire arrangements (and parodies) of all sorts of mainstream and other music, with much split-second use of tuned cowbells and car horns among much else. More serious musicians also have logistical problems with transporting their instruments: there was a radio documentary many years ago entitled 'Mahler needs a Jumbo' (i.e., if you are touring with performances of large-scale romantic symphonies, no smaller airliner will cope with all the players and their apparatus)

The click of the castanets is as evocative of Spain as the waft of garlic in the sun-baked streets around a bull-ring

The snare (like its non-musical original or counterpart) consists of lengths of snaggy wire which, when engaged ~ in loose contact with the lower membrane of the drum ~ produce a distinctive rustling sound

The coffee machine made its appearance in a dramatic setting by Matyas Seiber of William McGonagall's poem The Famous Tay Whale, and the 'crocks' during Donald Swann's enhanced arrangement of the slow movement from Haydn's Surprise Symphony. The typewriter appears occasionally in other composers' works, which may be why Hoffnung and co. avoided this then-everyday item

Do not confuse the tom-tom (defined at Answer 1) with the tam-tam, which, trivial though it may sound, is in fact a gong ~ whose larger sizes can shimmer through the sound of an entire orchestra. There is a wonderfully discreet use of this fine instrument in Debussy's orchestration of Satie's Gymnopedies (listen very carefully on the backbeats!)

This would be the hammered dulcimer, possibly as in the 'damsel with a dulcimer' in Taylor Coleridge's famous fantasy poem fragment Kubla Khan

The Celesta is the only one played from a piano-style keyboard; in each of the other cases, the struck components are laid out in the pattern of a giant keyboard, but (usually) made to sound by use of sticks or mallets

A handbell ensemble may consist of as few as 25 bells or less, or (in fairly extreme cases) several octaves'-worth of chromatic bells

A highly recommended work, not least in the original recording, made at dead of summer's night in Paris