Have some question about useing MQL5 cloud Network


I am newbie about mt5 strategy tester, I want to optimizing some EA , some article in online suggest to use MQL5 cloud Network for fastest optimize
i have some question about these

1. normally i use custom symbol from tickstory data ( real tick with Dukascopy data) , I found  MQL5 cloud Network do not support Custom symbol, So I want to know what is the source data is use to test... which broker data from , and real tick or not?

2. I have to open mt5 all time when I optmizing or not , or when it send any value to network , I can turn mt5 off?

Thank you