Spec's Yes Specifications are very important.

Usually I do all my own printing but sometimes my client has me bid and they bid also. They ask for the design specs so we would be on the same page right? wrong they like to pull the bait and switch you know you tell them what printing specs that you are working with and how it is part of the design but they want to think that they are getting a better deal by bidding something different and expecting it to still be spectacular. They agree, you go several rounds still confirming that they are printing the piece with the specs you gave them because these things need to be in place. For instance when you bid on a silk sheet maybe with some spot varnishes you design accordingly ie. using coated color swatches to get the color you are expecting when finished. I don't know how many times I have gone on press and they are printing on an uncoated stock and they are complaining about the color. Or when I have spent the time to set up spot varnish in my file to get there and see they aren't using any varnish. The frustrating part is that I like to have my files right when they go to the printers production team for several reasons, you can get breaks from printers if you are providing them with good files, it builds report and because I used to work in a prepress department and would be astonished at the files I got in from really good agencies and made me think lesser of them.
***side rant*** Please use a layout program like INDESIGN when laying out your project. Illustrator is not a layout program unless you are doing packaging.