Some of your questions are answered by this website, which contains a transcription of the original pamphlet describing biritch. Collison (the author of the pamphlet, and a railroad engineer who worked for a time in Turkey) apparently wrote a letter to The Saturday Review dated 28 May 1906, where he describes the history of the game. I quote:
Between 1880-4 I spent a considerable time in Constantinople and Asia Minor, where I played what was then called 'Biritch or Russian Whist'. I was then living, while in England, at Cromwell Road and introduced the game to many of my English friends, who liked it so much that they asked me to have the rules printed. ... 'Biritch' was attributed to the Russian colony at Constantinople; in my time the dominating social and political element. [not my ellipses, but the website's]
There were many variations of whist played in Russia, which this game was similar to. Mari-Lou in the comments has found a source that showing biritch is a variation of an earlier Russian game called yeralash. So while it's not clear whether the word biritch was originally Russian, most of the rules of the game are.
The word "biritch" means (in the game) no trump, although it is unclear whether this meaning is connected to its etymology. Maybe somebody who knows Turkish could tell us whether biritch might be a Russian mispronunciation of some word or phrase meaning "no trump".
More information probably can be found in the original version of The Saturday Review letter and also in another reference given on the above website: Thierry Depaulis and Jac Fuchs, "First Steps of Bridge in the West: Collinson's 'Biritch'", The Playing-Card, Vol. 32, no. 2, Sep.-Oct. 2003, pp. 67-76. Unfortunately, I can find neither of these online.
The obvious answer is that the thumb is not a finger. Otherwise it would not be called thumb but first finger.
In German a germanic language just like English we have:
- Thumb --> Daumen
- Index finger --> Zeigefinger
- Middle finger (the finger) --> Mittelfinger
- Fourth finger / Ring finger --> Ringfinger
- Pinky --> Kleiner Finger (small finger)
As you can see the thumb is not called finger. So the first finger would be the index finger.
Why is this the first? Because it is the most used.
Best Answer
While the image certainly splashes all over the screen, the immediate origins of the term might lie in the comic industry. A splash page or splash panel
A computer application's splash screen serves a similar purpose and was probably first introduced some time in the mid-90s. The comics terminology predates the software variant by a number of decades, possibly all the way back to before WW2. One source notes:
One can only be a little sceptical about the claim that the term was coined as a tribute to Eisner as it was in use well before his time, in the newspaper industry. ODO's entry for splash includes the following definitions:
From some time in the 1910s:
From The Making of Modern Journalism (1927):
ODO's entry also includes a note on the phrase "make a splash" which sums things up nicely:
A computer's splash screen (be it during boot-up, operating system start-up, or application start-up) does something similar by arresting the attention of the user with a pretty graphic, a bold title, and other miscellany while the application is loaded in the background. It is literally and figuratively making a splash on your screen.