Learn Russian: Журналисты спросили, уволили ли этого скандального актёра. - The journalists asked whether they fired this scandalous actor.

In English, we often use "if" for both conditions ("If it rains...") and indirect questions ("I asked if it rained"). In Russian, если is strictly for conditions. For indirect yes/no questions meaning "whether," you must use the particle ли.

How does the placement of ли work in this sentence?

The particle ли always comes immediately after the specific word being questioned, which is usually placed at the start of its clause. Here, the focus is on the action of firing, so the verb уволили comes first, followed right away by ли.

Could we use the doubt particles разве or неужели instead of ли here?

No, because ли simply reports a neutral yes/no question ("whether"). Разве and неужели express strong surprise or disbelief ("Did they really fire him?!"). If the journalists were expressing shock, you would more likely see a direct quote rather than an indirect clause: Журналисты спросили: "Неужели этого актёра уволили?"

Who is the subject of уволили (fired)?

There is no stated subject. Russian often uses the third-person plural verb form without the pronoun они (they) to express a general or passive idea. It translates naturally to "whether he got fired" or "whether they (the management) fired him."