4 holes type may be enough for fecal examination. Make sure the hole diameter and screw pitch is based on DIN standard. DIN is the German industrial standard and usually good microscopes are made based on this standard. This makes you possible to change lenses to different maker. There are several types of head to attach to the body depending on your purpose.
Monocular type is most simple and low-cost head.
If your usuage is only to observe through your eye and if you don't use it for long period in a day, monocular type will do. If you want to use for longer period and want to investigate further, I recommend you to get a binocular type. You will get less eyestrain. There is a prizm and an interocular distance adjustment mechanism. The bad part of binocular is, it will cost too much.