Is cancelling order and refund okay? Does it effect Gig promotion From Fiverr server?
I would avoid taking gigs that you can’t complete or have requirements that are beyond your skill set. Canceling an order that someone has from you will affect your cancellation rate and could “potentially” affect your rating or ranking as a seller.
It depends on the reason for the cancellation. If you had an order where the buyer did not give you all the information you need to complete the job and then the buyer never shows up to give you that information then you can contact customer service to cancel the order. The last time I did this it did not affect my gig stats.