People usually install Rear Rollpans more often than front rollpans, though both look great on your vehicle.
You need to remove your stock bumper in order to install your rollpan. You might need to relocate your lights and possibly your license plate as well.
A number of states didn't ask you to put bumpers on trucks until the last few years, if yours falls into that category, you're luck and should have no issues.
Differing bumper laws per state mean you'll have to check with your own local DMV to be certain. Normally you'll be left alone unless you cause trouble...or the local police are bored ;)
With your new smooth rear end you may now want to look at a custom tailgate or taillights. You can get tailgate skins with custom shapes cut into them for taillights.
Also, the lights from older cadillacs are a very popular look. You can get those with a Taillight Conversion Kit or Caddy Buckets which are metal frames that you weld into your bumper..