I assume the question is about the sentence endings and the difference? 'he HAS joined the army' or 'he joined the army.' If you add the 'has' joined the army, 'has' smoked' it means those activities have carried on for while, maybe a long while, so maybe he is still in the army, still smoking. without 'has' it means just one moment, it's telling you about a single event and not telling you if it has went on for a long time. Both sentences don't make a big difference to the 'since' meaning, they're just telling you how the person saying the sentence wants to describe the action.

'Get' implies a change from one state to another ie. you were driving along, then the traffic stopped. 'be' just explains your currently state. So if you get angry when you GET stuck, it means when the traffic changed. if you get angry when you ARE stuck in traffic that might imply you could be in the traffic for a longer period of time before you're angry. But.... in general they're interchangeable. There's no real difference anymore.