1. The fact had gone all abroad that the foreign crank who carried million-pound bills in his vest pocket was the patron saint of [Harris' eating-house]. That was enough. From being a poor, struggling, little hand-to-mouth enterprise, it had become celebrated, and overcrowded with customers. - Answer: Rags to riches. The excerpt refers to an enterprise that was once poor and struggling and has now become popular and flowing with costumers, refering it went form poor to rich or from rags to riches.
2. When the crash should come, he might somehow be able to save me from total destruction; I didn't know how, but he might think of a way, maybe. - Answer: Impending doom. The author states that a crash will come and affect him, thus representing a feeling of impending doom.
3. Deep in debt, not a cent in the world, a lovely girl's happiness or woe in my hands, and nothing in front of me but a salary which might never--oh, would never--materialize! - Answer: Wealth worship. The author refers to his poor economic situation as he is deep in debt and has now money ("<em>Not a cent in the world </em>"). He further claims his salary would never materialize, implying he would like to be wealthy.
4. Why, it isn't six months since you were clerking away for Blake Hopkins in Frisco on a salary, and sitting up nights on an extra allowance, helping me arrange and verify the Gould and Curry Extension papers and statistics. The idea of your being in London, and a vast millionaire, and a colossal celebrity! - Answer: Rags to riches. The author writes about how the person he refers to was once working on only a salary, going through night shifts to earn an extra allowance and now has become a "<em>vast millionare"</em> in London.
5. Please get those things off, sir, and throw them in the fire. Do me the favor to put on this shirt and this suit; it's just the thing, the very thing--plain, rich, modest, and just ducally nobby. - Answer: Wealth worship. The author is asking of a person to throw his clothing into the fire and wear apparel that would likely make him look wealthy.