What's your line of work?　　line of work 職種

職種はなんですか？

demanding  　きつい、過酷な

Here we use demanding in the case of "requires a lot of work, attention, or time".
A doctor might have a demanding schedule.
A student could be in a demanding class.
We also talk about demanding people, and that means they require a lot from others.
They're not easily satisfied, "Her professer was very demanding", for example, "He was always pushing her to think about the topic harder, make her analysis deeper", that sort of thing.

What do you like about ...?　...の何が好きですか？

What do you like about teaching English?