Default some help to understand :)

Please I want to know something so please help me to understand
I have LG G2 D802 (32 GB) with stock rom (4.2.2) I want to try a custom rom (kitkat) for example Mahdi rom what shall I do ??

If i make backup with TWRP for current stock rom (4.2.2) and format data&system then install custom kitkat and want to back again to the stock rom can i do this with restore it from TWRP ??? is that right or no ???????

please answer me

Sorry for bad English