To find the correct force first set the blade correctly as detailed below.. Then position the blade over the media, press origin, set the force to something low to start with (maybe 30) and while offline press test. If the little rectangle is cut out then check for marks on the mat where it cut, if there is more than a very slight scratch the force is too high.
If the rectangle does not cut right through, move the blade to a clear bit of the card, set the origin, increase the force by 10 and test again. repeat this process to find the force which just cuts the card but only scratches the mat below it.
Once you have found the force needed WRITE IT DOWN ON A BIT OF THE CARD. Then next time you come to cut that card you have a sample with the force needed written on it
Repeating a cut I am sure is simply a case of going offline and pressing repeat.. might be different in SCAL but try that and if it does not work as expected let us know.
The length of blade extending out of the holder should be set first, adjust the clicks until the exposed blade length is just a little more than the thickness of the card you intend to cut. You can if you wish just set it to the maximum blade length and be done with it but if you do you will have to be more carefull that you do not use too much force or you will cut holes in your mat!
The blade height is then set by loosening the clamp and lifting the blade holder, put your media on the mat and into the machine. Now place an old CD (NOT ONE YOU NEED) on the media and let the blade holder lower until the blade just touches the CD.. Now carefully tighten the clamp without letting the clamp or the blade holder move and remove the cd.