Not all carboard bike boxes are the same, I travelled twice, once with a specialized bike box, that was very sturdy and once with a BH bike box, that wasnt so sturdy and took some reinforcing with duct tape..
2 big advantages on using a carboard box, A) its free, B) it doesnt get in your way the next 50 weeks when your not travelling.
Depends on what bike your putting in it as to wether your going to go over your weight limit, I also put my pads and as much kit in the bike box as possible to help pad the bike out a bit, but another school of thought is to keep your kit seperate in case the box doesnt show up.
Some remove discs off the wheels too but I didnt bother with that and had no problems.
Take care packing it get a decent cardboard box and you shouldnt have too many problems.
Another tip is to put some tie down straps around the box to help you move it about. (if I get chance to travel again I might even fashion some kind of castor on the bottom so it rolled)
Check in is no problem, it doesnt go through the normal check in, they will direct you to an oversized luggage place and take it from you there.
Free Box.
Big roll of duct tape.
Tie down straps.