Wow, okay you have a lot to deal with. Rather than looking at multiple levels of equipment for different purposes, perhaps you should do a breakdown of your existing work and the percentages of demand in relation to the equipment. Rather than buying equipment to cover all of the possible types of work you have, you should focus on your core printing and use external trade houses for the specialty items such as NCR. Cutters are great, however, very expensive to maintain. Slitters and blades are not cheap. A decent guillotine would do all of that for you. In regards to minimum cut size. Stick with what you can do and get your clients to fit your limitations. For business cards under a certain size, you can make a cutting block out of card stock. For example. Business card at 50mm is too small for the gauge, create a cutting block at 100mm and set you final cut at 150mm. As long as it clears the guillotine clamp plate, you will be good to go. Keep your overheads low so if you get a drop in work, you dont have high lease payments and or cash in the bank. A lot of problems are created by designers who create artwork outside of basic industry standards, and print shops are trying to cover all demands. It not sustainable for small print shops.