i need to know how the whole cycle in odoo to process as below

1- I present expense need to pay to my mangers in advance before pay then after confirm i pay that but may be the amount be confirmed changed for example mobile expenses 500$ but i need to pay 499$ or pay 500$ then make settlement as amount paid 450$ , how do that on Odoo

2-how can i pay expenses from cash in Odoo

3-my manger approve to me get money for any expenses unexpected thru week this money as safekeeping account , so how manger approve on this money to issue and after that how i take from this money to make expenses need take approval from her then i need to pay from cash

I am talking on version 11 , awaiting your response