You may try Rutgers University Library, when I was there they had a whole
room of books devoted to NJ history and archival material.  Princeton
University might have similiar resources-they have books on their shelves
still marked University of New Jersey at Elizabethtown before they moved the
university to Princeton (In Colonial times!)  Also check out if there are any
local historical societies in the towns in which you are interested in the
skirmishes.  There was a small skirmish in New Brunswick.  I used the Rutgers
Library to get information about the colonial history of my home town of
Westfield, NJ including its brief occupation by British Troops who camped
there after a skirmish where they "chased the rebels into the hills"
(Watchung Mts.).  They then marched onto Rahway.  Having used the
Presbyterian meeting house as a slaughterhouse for all the livestock in the
area and stripping the village of most of its food they moved on.  The town
then had to petition Washington up in his Morristown for some supplies.  Just
an example of what I was able to find out about my hometown in the
Revolutioanry War just by using the Rutgers Library.  Good Luck