Hi, is it possible to take a bus from BCIA to Qinhuangdao with a pretty big luggage (25 kg)?

Hi,
I am interested in taking a bus from BCIA to Qinhuangdao. I will have a pretty big luggage (approx 25 kg), so is it possible to take a bus WITH this luggage?
I am asking, because I have read, that it is not convenient to have a big luggage.

What's more, I would like to ask about buying a ticket - supposedly I buy one let's say on 10 a.m. and then I go to the bus and wait till is full or it goes on the regular hours, according to the timetable?
Thanks for reply :)