The aileron stick of my homebuilt ultralight is stiff (hard to move) and the aileron itself can remain in its deflection angle hands free, is that a good thing?
The controls of any aircraft should move easily under the pilot's control. Large aircraft have hydraulic servos to assist the pilot, or even complete fly-by-wire systems, while smaller aircraft often have aerodynamic trim tabs which act as a simple assistance mechanism. On the ground, with no aerodynamic loads, the controls should move easily without such assistance, especially on an ultralight.
I would suspect that your control cables or pulleys are binding on something, or that the pivots of your cockpit controls or control surfaces are over-tightened. Either of these could result in premature wear and failure in flight, as well as the more obvious difficulty in maintaining control before failure. You should definitely investigate the cause thoroughly before attempting flight.