Learn Italian: Maria fa preparare il ricevimento al direttore dell'albergo. - Maria has the hotel director prepare the reception.

This is the key rule of the causative construction! Because the verb preparare already has a direct object (il ricevimento), the person actually doing the preparing (the agent) must be introduced by the preposition a. Here it combines with il to make al. This prevents the sentence from having two direct objects.

Could I change the word order and put al direttore before il ricevimento?

Yes, that is grammatically correct and perfectly natural in Italian. However, the standard word order you will usually see in textbooks is fare + infinitive + direct object + indirect object agent.

Does fa preparare mean Maria is forcing the director, or just asking him?

The construction fare + infinitive can mean either to make someone do something (forcing) or to have someone do something (delegating). Context is key. Since she is at a hotel, she is requesting a service, so having him prepare it is the right interpretation.

How would this sentence change if we replaced the hotel director with the pronoun for him?

Because the director is acting as an indirect object in this structure, you must use the indirect object pronoun gli. It goes right before the conjugated verb, making the sentence: Maria gli fa preparare il ricevimento.