You can replay past chapters for the kills you have not gotten yet. That being said, I got all the kills for all the weapons by chapter 15 or so, and that was without really trying. So it's very probable that you won't need to worry about a mop up session anyways.
There isn't (to my knowledge) an area to view your achievement progress. Every ten or so kills, however, the achievement counter will pop up on screen during game play.
Looking to boost anything I haven't completed. Especially arcade games.