Should a latecomer raise his hands with the takbeer when standing for the third rak'ah that he prays, or that the imam prays, or when he stands to complete what he missed after the imam's tasleem? And should he practice tawarruk in the imam's final tashahhud, or only in his own final tashahhud?

The places where one should raise the hands during prayer have been detailed in previous fatwas. A latecomer (masbuq) should raise his hands with the takbir when standing up from the first tashahhud. As for the takbir of the latecomer when he stands to complete what he missed, Imam An-Nawawi detailed it as follows: If the sitting from which he stood was his rightful sitting position, then he stands up with takbir. Otherwise, there are three opinions, the soundest of which is that he stands up without takbir. Regarding the latecomer's sitting posture during the tashahhud, the majority of scholars state he should sit in the iftirash (sitting on the left foot with the right foot upright) posture. Others hold that the tawarrul (sitting with the left foot under the right thigh and the right foot upright) posture is permissible, in imitation of the Imam.