At that age and mileage, it could be one or more of all things mentioned. The 2 biggies in my mind are the steering head bearings and swingarm bushings. The quick and dirty tests are:
Steering head: prop the front end up. Turn the fork from full left to full right slowly. At about dead front center, you may feel an "indent" like the stering wants to center there, then comes out as you continue to move the steering. If you feel that indent the bearings must be replaced, there is no repair. Stock bearings can be used and are good for about 10k miles. Tapered roller steering bearings are the rage and are forever. This wil cause very poor handlingand wobbles.
Swingarm: prop up the rear on centerstand. Remove lower shock mounts and pull shocks out of way. Grab the rear of the tire at its furtherst point rearward. Push and pull left to right. If you feel a clicking or see movement more than .5mm the bushings are shot. test #2: prop up, remove lower shocks mounts. raise and release the wheel. it should drop smoothly to its lowest positon. If its sticky or likely doesn't move at all the bushes are seized and need replacing. Note: rear end can make the front end drive poorly.
The wheel bearings are likely shot as well, but don't normally make the difference these others do.
