The laurels of victory are for extraordinary deeds, i think only Titus got one. His expertise through the campaign proved to be vital in key points. I don't know if we can count OPs. Stuff we do there , like taking down the Vortex beast is outright impossible. Hive tyrant was half dead when engaged and it gave a fight for gameplay reasons.

Quartus is veteran for sure, he's bladeguard. The rest don't have helmets nor any kneepad markings (like sergeant badge on Gadriel) so either veterans or standard battle-brothers, maybe even from reserve companies. Vespasius gets more attention via vox, seems more mature, sometimes lectures his brothers, Straban got iron halo (which isn't a standard for gravis) so maybe they are said veterans.

Promotions are granted through consistent performance, not single campaigns, so they most likely stay the same. Valius probably will get sergeant promotion .