The reamer/awl is used for poking holes mainly...in plastic, cardboard, etc. You can also "drill" it into wood to make a dent before you drive a screw.
The wire scraper is just that...a wire scraper! Use it to take the insulation off wire. I use the wire cutters to cut the insulation, but some prefer that scraper tool.
The crimpers are actually the reverse of the plier heads...under that main plier pivot you'll see both halves of the metal come together when you close the tool...put the thing to be crimped between those two parts and squeexe.