I am trying to disassemble the front column in order to treat the rust problem. I cannot see how this comes apart.

wheel hubs are cast steel and are not rust treated. The rust may be from driving on snow/ice roads that have had salt on them. There is not much that can be done .You can trying a rust control agent ( phosphoric acid) which can be bought concentrated or in diluted form in rust prevention undercoats. You could then try using a good rust control paint that will withstand a lot of heat (remember that the brakes make everything hot)
If you can find an electro-plater in your area you may get the hubs cadmium plated or zink plated and this will arrest the rust.

Sand blast the rust and treat with several products they will arrest the rust. There use to be a product called TR7 and NAPA has a rust arrestor, then I would paint and or undercoat with rubberized undercoat. Make sure you start way from wires and fuel lines and exhaust areas

Take the brakes apart & look for the problem

Brakes have to come apart once a year anyway,
to remove rust,inspect & lube & you flush the brake
fluid every 2 years,on all vehicles

Maybe the rubber flex hose is restricted or the calipers
& fluid are neglected & everything is just rusted & nothing
works

There are at least two causes for this. One is the sterring nut (large nut at the top of the handlbar mounting area) is suddenly too tight. Not likely unless you recently worked on that area, these tend to get looser over time rather than tight.
Second likely cause is that the bearings in the sterring column are worn or even rusted,
One other cause could be that the steering column is bent and binding a bit. If you have ridden over any especially rough areas or dropped the bike or hit something full on with the front wheel could be causes for this.

Suggestions:
Check the torque on the steerling column nut.
If that is good, disassemble from the top and inspect the bearings. While you have it apart, see if you can determine whether or not the steering column is bent/warped. You can do this by laying it on a clean smooth surface and roll slowly. Observe the ends and center and see if any gaps show up while rotating it. If it is bent, there is nothing to do but replace.
Should likely replace the bearings if you have gone this far anyway. Clean everything thoroughly and grease it up before you put it back together. Shop manual will provide details on procedures and torque values, etc.

So take your brakes apart & do what ever service needs to be done

They should come apart once a year

If your not doing that ,disassembly,rust removal,lube
& any machine work, if necessary,your going to have
braking problems

The fluid gets changed every 2 years,so there is no excuse
for not being in there looking things over

That will be very difficult to find. Your best bet would be take it to an auto body shop. and have them treat the rust and weld a panel over the old one and treat it with rust proofing. if you plan on keeping it for a long while.

You have a rusted rotor,stuck on the hub???
Has it set for eons???

http://www.pdfoo.com/

if you have floating rotors in the front then no.

But if you have locking hub units in the front then yes the bearing will have to come apart.

But if there is only one nut and you can see the threads through the wheel then no you have floating rotors, and sometimes are rusted to wheel bearing and are a pain to get off. Call the parts department and ask whether these are floating rotors or not. This will clarify everything

The connection between the Lock cylinder and the Ignition switch has come apart. There is pin that holds it together where the column tilts to allow for the tilt. The bad thing is the column needs to be completely disassembled to fix it, or replace the column with one from a salvage yard. The pin that falls out is usually still inside the column if you take it apart.