I am always fascinated by the quality macro shots I have looked at, in particular those of insects. Not having delved into this yet, I am wondering about how much (if any) cropping is applied to those shots.

Generally speaking, when those shots are taken, is the main subject (eg the insect) taking up most of the viewfinder or is it only taking up a small portion of the viewfinder and the output photo is then cropped just to localise the macro shot? I hope this makes some sense, I'm not sure how to better phrase my question.

With general photography, is cropping mainly done to improve the composition of a photo and are there rules as to what dimensions the cropping be done to? And how does this cropping affect print output (i.e. would you have to physically trim a print because of the crop ratio you have used)?

Sorry for so many newbie questions!

Thanks Scott