help ! buying tickets at Queen Elizabeth box office

[moneytech]

So I am trying to get 10 tickets to an up and coming show at the Queen Elizabeth Theatre in Vancouver BC.
If I buy it online at ticket master, I would get dinged around $8 in convenience fee PER TICKET. I heard that you wont get charge this fee if you buy it directly at the box office.
Is that correct ? If I do want to buy at the box office, it says box office is open 2 hours before performance, does that mean you can only buy tickets for that night's performance only or can you buy future events or even future different unrelated show as what is performing that night ?
Would this be generally be true for all box office ?