есть учебник ли у него?
More natural way to ask is "Учебник ли у него?" without "есть". This question implies that we know the he has something but we have some doubts that that thing is a textbook so we need to know whether it a textbook or not.

The thing with stress works with Russian as well:
У него есть учебник? Has he a textbook?
У него есть учебник? Has he a textbook?
У него есть учебник? Has he [really] a textbook [and not something else]? Here it looks as if we have some doubts that what he have is a textbook.


Теперь vs. Сейчас
Сейчас - now
Теперь - now with some meaning of comparing now vs. past
Though using of these words is context sensitive.