if i buy a new headunit will i still be able to use the controls on the side of the car

 

You need an adapter for the head unit to operate with the dash controls. Get a Modifry DCI (dash control interface). There are a couple different models depending on which head unit you get. The man to talk to is Bob. Modifry is his screen name here, and he will answer your PMs or visit his website (Modifry.com I believe).