Daf Yomi - Sukkah 46 - Shehechiyanu by Reb Jay

A Shehechiyanu is said on the lulav on the first day, and the brocha on the lulav is said once a day (on the first seven days of sukkos), even if it is taken many times. Unlike on other mitzvos of Yom Tov, where the brocha of Shehechiyanu is said both the first and second day (Pesach, Sukkos, Shavuos, the Shehechiyanu on the Shofar), the Shehechiyanu on the lulav is only said on the first day. One reason is that the Shehechiyanu said on the second day is for Yom Tov itself, and the second day always has the din of the first day (Sefika D'yoma). The exception to this is shofar, though, in reality, it is not an exception, as the mitzva of shofar on Rosh Hashana is intrinsic in the day itself (Rosh Hashana is called Yom Hatreuah in the Torah), as opposed to lulav which is a mitzva on the day, not "of" the day. The Mishna Berura says another reason, that the brocha of Shehechiyanu is said both days of Rosh Hashana is because sometimes the ikar day of Rosh Hashana is the second day (Sefika D'yoma), and as we mentioned, the shofar defines the day.
A brocha is not said on the making of the sukka. The Mechaber writes that a Shehechiyanu should be said, but we are yotzei with the Shehechiyanu said on the first night. The Sheiltos D'rav Achai Gaon says that the making of the sukka is a mitzva in itself (Chag hasukkos ta'aseh lecha) and requires a brocha. L'choeroh, it would also be a nafka minah with regards to oisek b'mitzva patur min hamitzva, as most shitos say building a sukka is hechsher mitzva and would not be considered oisek mitzva, with the Sheiltos considering it a mitzva, thus building the sukka is oisek b'mitzva and one would be patur from another mitzva.