CoLos charge based on the number of Racks (or part of a rack) that you require. If you have a cage then they charge either by the rack or by the square foot.
For the power that is needed they will charge you by the KW for the power that is needed.
For the bandwidth you’ll pay for a guaranteed amount of bandwidth. If you go over that you’ll have to pay for bursting. For example you could order 100 Megs of bandwidth. If you go over that to 110 Megs of bandwidth you’ll have to pay for the extra. Bandwidth measurements are done based on averages so if you go over a little you aren’t totally screwed.