If I recall, in previous lessons we didn't have to use articles when using "ni", why should we use now?
Definite articles are retained, only indefinite and partitive articles are dropped.
Why is "ne payais jamais” used sometimes and "ne jamais payais” in others?
I don't think ne jamais payais occurs anywhere. But if the verb were in the infinitive, you'd put the whole negation (if you see what I mean) in front of it: ne jamais payer.
In the French sentence, I would take cafés to mean cafes - small places where you buy cofee and food.