Here is a link that will explain what a 1 piece crank is and looks like. If yours does not look like this then it is a 3 piece. http://www.sheldonbrown.com/opc.html
We typically recommend our kit to folks with some level of bike wrenching knowledge, but the instructions are easy to follow, IF you take your time and not rush things. Make it an enjoyable process.
I guess the big question is: The piece your pedals attach to, is it one whole piece for both pedals? Or is each pedal attached to it's own crank and each crank attached to a center spindle?
Thats a 3 piece crank, its right for the kit but what you will need is a tool to remove the cranks or have someone remove them and the replace the axle yourself.
Not a huge deal but be prepared to have the proper crank removal tool or at the very least some kind of gear puller or maybe even a harmonic balancer puller. Cranks can be tough to get off without the right tool.
No problem then they can pop em off in a matter of seconds with thier tools. You might want them to put the axle in as well but its usually no big deal and you dont need any special tools to put the new cranks on...just tighten them down...oh yea......