You can keep it in the chunky soil – if it’s putting leaves out I’d keep doing what you’re doing! As for fertiliser, they really not fussy.

Any houseplant fertiliser is fine. Without knowing the exact mineral composition of your soil and water it’s basically impossible to get one that’s perfect (and explains why results vary wildly from plant to plant).

Dynagrow is very popular because it’s meant for hydroponics, so it contains every nutrient your plant could need. I use generals hydroponics flora series, but it can be a faff mixing up the solution as there are three different components.