1 Yes. In different conditions and aircraft will need trimming. In a dive for example it may become nose heavy and this would be corrected by trimming the tailplane/elevators to compensate. Deploying flaps or undercarriage almost invariably causes changes which would be compensated for by the appropriate adjustment in trim.
2 Not all aircraft have the capability of trimming all those surfaces. The early Bf109s had no rudder trim (apart from a preset tab which could not be altered from the cockpit and when flown fast needed a constant rudder input,very tiring for the pilot's left leg. The ailerons were trimmed on a Spitfire,which had no trim tabs,not even the bendable metal tab favoured by the Germans,whilst on the ground,by hammering the trailing edge with a mallet!
Where trim tabs are present they would be variably controlled,often by rotating a wheel,thus giving fine control and infinite settings within their range. There are many different types,some simply worked by a mechanical linkage some are powered.
Cheers
Steve