As Greg said, meet with the company or individual that will cut your sheets. I do have a large 4′ X 8′ CNC and do a lot of outside work for customers. Any competent individual will be able to import the DXF files. With the updated features coming in CabWriter 2.0 – specifically the ability to have the tongue and grove – make sure the understand that and can execute that feature. Most DXF files will have that information embedded in the drawing and in my case it is just a macro that I need to run to ensure it translated into the proper dado or tongue depth. Also since 3/4″ plywood is not .75″ the programmer will have to measure the sheet to ensure they have the proper depth. When cutting with a CNC, you can either go off the top or the bottom of the material. On sheet goods, I always go off the bottom which ensures the tongue is always correct.
I would make a simple one sheet cabinet and let the individual run it to ensure it met my specifications – don’t use an expensive prefinished sheet, baltic birch plywood (5 ply) would do. Give the individual the measurements so they can validate their tool paths. Since I deal with wholesale companies that deliver to my shop, most customers just send me the files and I get the product delivered to me. Why would you want to handle the sheets twice. If are getting better prices, have your company deliver the product to the CNC shop.
One of the other questions I would ask is what is their lead time and if I had a rush job, how little time could they pump something out for me. I stay very busy and customers are always calling me for jobs; the first thing I as is what is their time frame. There are times that I have jobs already scheduled back to back and do not have a lot of leeway – the sheet breaks loose or I have programed it wrong and have to run a sheet again. The other day I did three doors for cut glass inserts and the customer somehow cracked a door and he needed to finish the job; I had to work him into my schedule so he was not late. That impacted my next job – I had to work extra hours in order to catch up.
Not that it makes much difference to you, but ask what software they are running. Someone specializing is just doing cabinets and running Mozaik or CabinetPro may not be able to import the DXF files, I am just not familiar with their programs enough to say. These are expensive programs with monthly fees or just cost a lot and only focus on cabinet designs and cutting.
I hope this helps from someone who has a CNC and cuts customer’s jobs. As I was typing this I got a call and have to call the customer back to get him scheduled.