Backup and custom rom topic

Hi, last week my sister gave me an ace, s5380L, i did root on the phone, installed cmw and did the wipes to flash the aceone v2.2 rom . The rom work very nice.
Before that, i did a backup from cmw , what i want to know is :
if i restore , what is going to back? the stock rom of the ace?
if i want to flash another rom , can i restore, then backup, and then do all the wipes to flash a new rom?
thanks!
sorry for my bad english.