Prop Shops, HFTs and Hedge Funds

Quantative Researcher is a very niche job profile common in these industries. I wanted to understand what are the techincial skill sets required to pioneer in this line of industry. 1. What financial concepts are good to know for its day to day req. ex Voltaility Curves, Stochastic Finance, product knowledge like Options and Futures etc. ? 2. ML/DL are being applied more and more and given ML/DL is a vast field, what are the common fechniques which are applied more frequently. 3. How much does the role involves developing tools for the traders?