Yes.
To program a Motorola CDM model radio, you need the Professional CPS software that is available from Motorola.
You also need a programming cable to interface the radio to your PC. Programming cables vary, and you can use USB cables that directly interface between the PC and radio, or you can use the older Motorola style that need a R.I.B. (Radio Interface Box) to work.
A legal copy of the software is going to run you upwards of $300. After market cables (these can be a real crap-shoot) can run for $30 or so on up. A "real" Motorola cable can be $100 or more.
If you are just going to program this radio once, you may want to consider having a radio shop do it. It isn't impossible to do yourself, but it isn't necessarily cheap or easy for the first timer. Many people figure out the programming software on their own, however you need to be VERY careful if you haven't done it before. Making and error and accidentally causing interference to other radio systems can get you in some trouble.
Antennas:
Yeah, pretty much whatever you want. You do need to know some things first:
Most of all, you need to know exactly what frequencies you will be transmitting on. The antenna needs to be tuned to work on those frequencies. Again, this may be something you'd want to talk to a shop about, but it isn't hard to do on your own.
Antenna mounts are available in magnetic mounts, trunk lip mounts, permanent mounts, brackets, etc, etc…..
I'd suggest getting an NMO style mount and antenna, it is pretty much the de-facto standard for professional radio systems and will give you the most flexibility. The mount needs to have enough cable to reach from where your radio will be mounted to where your antenna goes. It also needs to have the "mini-UHF" style connector on the end of the cable to match the antenna connector on the radio. You can purchase the mounts with the connector already installed (strongly recommended if you haven't installed coaxial cable connectors before.
Power: You need to have a suitable power supply for the radio. In a vehicle you need to feed that preferably comes directly off the battery, fused at the battery end, safety and securely run to the location where the radio is mounted.
Tapping into existing wiring in a vehicle can be problematic. Noise issues, overloading the circuit, etc. are all things to consider. There are cigarette lighter power adapters for CDM radios, but you need to pay attention to the power consumption of the radio and what the cigarette lighter socket will provide. This can still result in noise issues.
For the antenna mount and antenna, take a look here:
"L" bracket mount with Mini-UHF connector:
http://www.theantennafarm.com/catalog/laird-tech-mb8umi-lbt-1675.html
Magnetic mount with Mini-UHF connector:
http://www.theantennafarm.com/catalog/larsen-nmommrmpl-1092.html
You didn't say which band you will be using this radio on, so it's not possible to recommend a specific antenna. You will want an NMO base antenna to match one of the mounts above. CDM1550's come in VHF Low Band, VHF High Band, 220MHz band, UHF band or 700MHz band. You will need to select an antenna that is designed to work on the frequencies your radio works on:
http://www.theantennafarm.com/catalog/antennas-191/mobile-antennas-192/
It's not difficult to do this, it just takes some research and patience. Don't be slow to ask for help, and don't be afraid to talk to a radio shop if you are not comfortable doing this yourself.
Also, as I'm sure you know, you need a valid license to use these radios, no exceptions. Land Mobile, Business, Public Safety, Amateur Radio, GMRS, etc all require licenses in the US. In other countries, the rules and frequencies may vary, but it's a good idea to check with the proper authorities.
Nothing wrong with just listening though. These radios have great receivers and they'll often outperform a consumer grade scanner.
Good luck!