1) The main idea of the  suni's and shi'is part is that both schools of thoughts are now considerate as Muslim brothers. Their relationship have developed  a certain degree of  coorporation under the condition of modernity and in the face of western presence . However , There is always a tension between Shi'ism and Suni's that leads to war , violence and crimes.  

2)  The Shias accept some of the same hadits used by Sunnis as part of the sunnah to argue their case. In addition, they consider the sayings of Ahl bAYT that are not attributed directly to Muhammad as hadiths. Shias do not accept many Sunni hadiths unless they are also recorded in Shia sources or the methodology can be proven of how they were recorded. Also, some Sunni-accepted hadith are less favored by Shias; one example is that because of Aisha's opposition to Ali, hadiths narrated by Aisha are not given the same authority as those by other companions.