The reds under high magnification look like stacks of bricks, actually you are seeing cell walls. Other carbonate allochems include the ooids also know as ooliths or ools. The root of the name comes from the word for egg for which these were originally thought to have been. Watch out for brachiopod spines. They might be of fecal origin but not exclusively.
Shape can vary widely.
Intraclasts are cryptocrystalline calcium carbonate grains, which are larger than medium sand in size. Think of them as big pelloids. Limestone will have varying degrees of terrigenous detritus or material reworked from pre-existing strata or transported from outside the depositional basin. Avoid using the term interclasts, use lithoclasts instead. Between the above grains one can find pore spaces and micrite .