I just had an idea, would it be possible to make the servo run in one direction (for 240 mili sec required to move 90 degrees at 5 V) than halt it for some time and then move it in the other direction (for 240 mili secs again). This should produce the same results int theory respective of the degrees of rotation. Is this correct ?
In theory it would. However you will find in time that the servo wheel will gradually drift it's orentation and you will not be able to keep the stop positions fixed to absolute positions.
Servo are available in all sizes, torque values, speeds, etc. Just stay away from servos that say modified or continuous rotation. Google has plenty of links to servo vendors. http://www.hobbypartz.com/servos.html