amaru, first of all are you using a joystick or the keyboard? If keyboard, hats off to you, I've never got the hang of it. If you haven't got a stick, even a cheap two-axis one will transform the game for you.
Secondly, about trim, all the Boeings have trim indicators. In the 737 and 777 they are small wheels on the panel, with gauges giving you the trim position in terms of degrees up or down; the 747 is different, the indicator is on the throttle pedestal, which you have to call up.
But, in any case, the indicators are only useful for setting the trim before takeoff; in flight, they don't help because you have no way of knowing what setting is appropriate to a given situation. The correct method is to watch the nose of the aeroplane, and/or the 'rate of climb and descent' gauge, and trim the aircraft to fly straight and level at a given airspeed. In level flight, depending on the fuel load etc., most aeroplanes fly 'level' at between 2 and 3 degrees upward trim.
In any case, if the autopilot is 'on,' it will be handling the trim itself. It will immediately 'unwind' any trim setting you put in.
As for the approach, 140 knots is fine for almost any airliner. 180 is way too fast. In any case, one shouldn't confuse 'approach speed' (say 140) with 'landing speed,' touchdown speed, which is much lower. Nor should you try to land with the autothrottle on. Normal practice is to turn the autopilot and speed hold off at about 1,000 feet (or 500 at the latest), cut all power as you cross the threshold, and then 'flare' - ease the stick back to raise the nose, and then hold that position while the speed drops off and the aeroplane 'settles' by itself. Again, glance at the 'rate of descent' gauge and try to get it down to about 200 feet a minute.
Touchdown in an airliner usually occurs at about 110 knots. And the very best landings are the ones where even YOU don't know exactly when you're going to hear the wheels start rumbling!

Step-by-step guide and more tips here:-
http://www.simviation.com/cgi-bin/yabb2/YaBB.pl?board=COF;action=display;num=1111322151Hope some at least of all that helps.