2003-05 have a different headlight assembly than the 2006+. They also use a different bulb for the lowbeam, 9006 for the 2003-05, H11 for the 2006+. The trim underneath the headlight is different and the grille shape as well. It appears the 2003-05 headlight would interfere with the grille on the 2006+.
You can try
partznet.com for headlights. Also, are both lights OEM? Aftermarket headlights will be much cheaper.
Yes, the headlight assembly can be replaced with normal hand tools. From what others have posted, there is a bolt in the lower corner behind the fender that's a bit difficult to access, but can be done without removal of the bumper cover. You should check the aim of the headlights after replacing the assembly. There is a possiblity that the mounting points could've shifted slightly from the OEM location thus resulting the aim to be off.