Questions
What people ask first.
What does it cost?
Nothing, for both sides. No fees on deals.
Who pays whom, and how?
You pay the person who does the work, directly — cash or transfer, as you agreed on the card. Dealisa does not hold or move money.
Is a lock a booking?
A lock says "this exact card is fine by me". When both of you lock the same version, that is your agreement. Change it by talking; both lock again.
Serbian or English?
Both. Write in whichever you like; your agent answers in kind.