Learn Italian: Legga il bando riguardante l'ammissione. - Read the call for applications concerning the admission.

Yes, riguardante is the present participle of riguardare. In this sentence, it acts as a verbal relative clause, meaning exactly the same thing as che riguarda (which concerns). At a B2 level, using the present participle like this is a great way to make your written Italian sound more formal and professional, which fits the context of an official document perfectly.

Does 'riguardante' change depending on the noun it describes?

Yes, because it functions as an adjective here. Present participles end in -e, so they don't change for gender, but they do change for number. If you were talking about multiple calls for applications, the phrase would become i bandi riguardanti l'ammissione.

Why is the verb 'leggere' conjugated as 'Legga' here?

Legga is the formal imperative, which borrows the present subjunctive form for Lei (formal 'you'). Since a bando is an official document, the speaker is addressing the listener politely. If it were an informal conversation, the verb would be Leggi.

What makes a 'bando' different from a normal announcement?

A bando is a formal, official call for applications or a public notice. It is typically issued by universities, public administrations, or organizations for things like admissions, scholarships, or public jobs. It carries much more official weight than a general annuncio (announcement).