There’s a machlokes haposkim whether you have to honor all your older brothers or just the oldest. It is best to be stringent and honor all your older brothers. It should be noted that Gilyon Maharsha and Bais Lechem Yehuda bring from other sources that this obligation is not for any brother that is older than you, only the oldest of the brothers. It seems clear that the obligation includes even a brother who is not the oldest in the house and is preceded by sisters. This halacha does not apply to an older sister according to the poskim, but one should treat her with respect as they should with all people older than themselve.
Are you obligated to stand up when your older brother walks into the room? The Shevet HaKehosi discusses this issue in 1:262. He says that the Bais Meir points out that when it comes to a big brother you are only obligated to give him kavod, but there is no chiyuv of Morah, to fear him. The Sefer Chareidim holds that standing up for someone falls under the category of kavod, and so it seems also from the Shulchan Aruch. On the other hand the Shaar Ephraim and the Makneh both hold that standing up is a matter of morah and not kavod, so you might not be obligated. However, the Brisker Rov in Chidushei HaGriz (Hilchos Talmud Torah) holds that you are chayav in both kavod and morah of your big brother.
Since many poskim hold that the obligation of honoring your big brother is Min HaTorah, the Shevet HaKehosi says you should be machmir and stand up for him since it is a Safek D’Oiraisa.
The obligation to honor an older brother applies even if the younger brother is a Talmid Chacham and greater in Torah than the older brother. (Rama Yoreh Deah Siman 240:22)
One is also obligated to honor their uncles and aunts (as long as their fathed is alive.)