I picked up an A2 style Bushmaster M4gery about two weeks ago.  Finally got to try it out this past weekend and burnt my fingers but good!  

Will the CAR type handguards help keep the barrel cooler or should I just go ahead and spring for a forward grip?

If you're referring to the M4 type HGs, they will give you less heat to your hands.  The down side is that they dissipate the heat more slowly, so the barrel wil get hotter more quickly.  

I have seen one suggestion to take a set and cut the inner shield out of the top HG, while mainraining the double shield on the bottom piece. This would give you the heat protection on your hand, while dissapating the heat faster thru the top.