How to check the PCB design for manufacturing(DFM)
Most PCB shops will work with Gerber and Excellon drill files, which your PCB design software should be able to create. If it can't, dump it and switch to a decent EDA package.
While Gerber is a good standard which should avoid a good deal of possible misunderstandings you still need extra documentation files. Talk about it with your shop, what do they need? What format? Layer stacking is one thing which comes to mind.
While your EDA software can automagically create Gerber files from your design you still want to verify those, since there are many options and a small mistake may go unnoticed. There are several Gerber viewers around, for instance there's the free GC-Prevue.