to install caliper brakes you must have a crossbar positioned at a suitable distance from the rim, between the seat stays, with a hole drilled into the center of it for the bolt which is the pivot for the brake arm levers. on the front fork, there must be a hole drilled for the bolt. some newer styled front forks have an extended stem, with the forks welded alongside it. the longer stem is drilled for the caliper pivot bolt.
center pull rim brakes and linear pull brakes require a special lug welded onto the seat stay or front fork leg for the brake arm pivot.
Disk brakes require a hub capable of accepting a top hat adapter for the disk, or a purpose built hub, and lugs welded on the stay and fork to support the caliper. Disk brakes are available with cable or hydraulic operation.
there is also a center pull style of brake called a 'bulldog' which pulls a triangular wedge up between the two brake arms.
not to be forgotten will be the drum brakes offered by the asian manufacturers, which might be a good option!
Have I omitted anything?
Would pics help u makes decisions on this?
Best
rc