Learn Dutch: We zullen de limiet nagaan. - We will check the limit.

Because it is used here as a full infinitive alongside the auxiliary verb zullen (will). When a separable verb acts as an infinitive at the end of a clause, its prefix and base verb are written together as one word. If you used it as the main active verb in the present tense, it would split: We gaan de limiet na (We check the limit).

What is the nuance of nagaan compared to other verbs for "to check", like controleren or nakijken?

nagaan means to investigate, trace, or ascertain the facts to see if something is true. controleren is more about inspecting or verifying against a rule or standard (like checking tickets), while nakijken is often used for reviewing or correcting (like a teacher checking homework).

Does zullen just mean "will" here, or is there a deeper meaning?

While zullen is primarily used here to form the future tense ("will"), it often carries a strong tone of intention, commitment, or a promise in Dutch. Here, it implies "We intend to look into it" or "We promise to investigate the limit."

How does a sentence like this set up indirect questions with in hoeverre?