Yes, in the passive form, the past participle will take the number and gender of the subject. As for the auxiliary être, it’ll follow the standard passé composé conjugation.

• rapport is masculine singular, so it should be

  Le rapport a été fait par Grégoire.

• Julien is a boy’s name. Also, the past participle for attendre (to wait for) is attendu, not atteint (which comes from atteindre, to reach)

  Julian est attendu par Louise

• matchs is masculine plural (note that the tense of this sentence is not passé composé, but present)

  Les matchs sont regardés par des milliers de spectateurs

• nouvelle is feminine singular (same as previous sentence, this is present tense)

  La nouvelle est annoncée par la presse

• chateau is masculine singular

  Le chateau a été construit par l’architecte

Passive voice is obtained with “être” as an auxiliary verb. Être is conjugated with the appropriate tense and followed with the past participle of the main verb.

One example in present tense:

La souris est mangée par le chat.

To build passive with a compound tense, the same applies. The “être” auxiliary is conjugated using the “avoir” auxiliary (conjugated avoir + été) and the past participle of the main verb follows.

This example is in passé composé tense:

La souris a été mangée par le chat.

Concerning agreements of past participles, only the one from the main verb receives distinctive inflections for feminine or plurals according to the same rules as for the active voice. Notice that the auxiliary of the main verb is always être. Hence, the agreement is made with the subject (here la souris), not with the agent (here le chat).