Welcome to the forum LC. I think that the capabilities that you want your machine to have are well within the performance parameters for most of the plans mentioned. The only thing I will point out is that you will only get a couple inches of Z height out one of these machines, which could be an issue if you want to cut tall blocks of foam.
The JRGO plans are really good. It does, in my opinion, require more fabrication time than others available. I have not used the hobbycnc or rockcliff plans, but I am sure others can comment. I do however have the Solsylva plans so I can comment on them. I think that you would do very well with the plans. They are simple and very well thought out. You can purchase almost all the materials at a big orange or blue store. The plans take you through every step and are meant for first timers. The book you get has 4 machines any of which will meet some portion of your needs. The smallest one can be built for under $100 and coupled with a hobbycnc controller will run you under $400. Definitely worth checking out...
EMC2 will meet your needs for the controller very well. It is very powerful and can control much more complicated machines than the one you are looking it building. However, the controller is only 1/3 of the picture with software. You need to think about the CAD and CAM packages you want. I would go with the cheapest you can find at this point. I think that CamBam is still free and that it can import from AI and other drawing programs, so that might be the way to go.
If you find you like the hobby, then I would recommend stepping up to better software. For CAM, I would recommend Vectric's different software packages. Cut2d will give you the ability to machine wing ribs and other 2.5d bracket structures. If you want to do a 3d part, Cut3d is also very good. For Cad, take your pick...I tend to use SolidWorks and AutoCad, but those are way too pricey for most people.