1) Display is a 16x4 LCD Display without backlight;
2a) we will have to solder them ourselves
2b) components will be in a PDIP package

I extracted the above from your document and

1) I would never use a LCD w/o backlight, the added cost - forget it. Compared to the added user friendliness that cost is nothing.

2) to make a design you can still use 5 years from now go surface mount. You get a better, smaller product and the failure rate will be greatly reduced. This, of course, means contract manufacturing.

Someone mentioned 'modular' - forget it. If you forsee an expansion, include it in your design and make the components DNI (Do Not Install) for now if you need. With todays component prices it is usually the best idea to include all and disable some in software, then you can 'upgrade the hardware' and charge for it easily.

Erik