patrol boro's are the management for a group of pct's
taskforce is a boro wide pct, they do not use cars marked with PBBS,PBMN etc. it would be BSTF MNTF etc. i do not know anything about slowly relettering, i been with the nypd since 2001,and they always been this way
taskforce goes to high crime area's and when requested for a bigger crime or mobilization
if you see a rmp such as pbbs impact, its a loaner car assigened to impact units from the pbbs boro
boro channels, are used for operations such as details, under cover ops etc. it is not simplex, it has a repeater,but no dispatcher present, if needed a dispatcher can be plugged in.....