Since this is mostly about one mechanical aspect of markets - what is a "bid/ask" spread - it applies beyond the stockmarket to crypto markets. Except those tend to have fewer rules about the order book.

If you're trading indirectly, which is not unusual with a brokerage, you should be aware of what is meant by "best execution", and I offer this article with an explanation in FX: https://medium.com/bull-market/oranges-and-lemons-the-fx-sca...