1-Yes it is equally divided in two halves both parts are exactly 10%.
2- it is according to all Maraje.
3-for the distribution of sahme sadaat permission is not required according all Maraje except Aagha e Khamenei
As per the ruling of Aagha e khamenei. You must deposit to his office or his representatives.
4- In this case contact Wakeel (representative) of your Marja