1) The number one used material is PLA; a bio-degradable non-toxic plastic that is a lot easier and dimensional correct (when printing an object). The second widely used material is ABS. The PSI rating of PLA is around 4000, but it is brittle compared to ABS (about 6000 PSI). They can cost anywhere from $20-60/Kg. It varies between brands.
2) My printer setup is a little over $2K now. Factor in the optional second extruder, spare parts needed, RaspberryPi to run it remotely, networking equipment, backup battery in case the power goes out, etc. I put a lot in, because I know the better quality is worth it in the end. Oh, and this was a kit that still needed 40+ hours to build it!
Cost varies to make things, based on your equipment life analysis and materials per hour. Like every piece of equipment, you have to “expect” a time where it will have to be replaced. Usually $0.30+/CCM (cubic centimeter of material) is a healthy profit for me. The printer has a defined role for my company, and using it to print on 3DHubs is just a bonus. Like using your car in your spare time to Uber. I won’t tell you the specifics on what my company is doing, at least not on here. Just because it is not patented yet.
3) It depends on your equipment. My printer has the ability to print at 100+mm/s, accurately. Which it isn’t very common, since the average speeds are 50-70mm/s. That also means faster print times. Lowering your layer resolution from 100 Microns to 300 will also theoretically slice your print time drastically. A larger build volume can also allow for multiple objects. For instance, I am printing multiple parts on my printer as we speak.
4)
Step 1: Verify CAD files from the client. If no files are provided, offer CAD services at a great rate.
Step 2: Setup the settings; toolpath alterations (if needed), supports, rafts, density, temperatures, retraction, resolution, part placements, etc. in Simplify3D. It’s not a free program, but it is worth every penny
Step 3: Over the network, start setting up the printer’s temps, and load up the G-Code file.
Step 4: Set up the print bed, hone the printer’s axis’, and verify the performance/ability of the machine.
Step 5: Start the print
Waiting, and checking up in person or over the network…
Step 6: Remove part, and remove the supports and/or rafts.
Step 7: Notify the customer that the part(s) is being shipped or ready for pickup. I will include photos, and typically a timelapse video of the print.
Step 8: Pat yourself on the back for helping out a fellow artist, tinkerer, entrepreneur, or the like! 
This may be a little too detailed, but I figured what the hay! Haha
I’m very transparent about my operations, and my customers like that. If you have any more questions, and would like some samples of the materials (and even videos of them being printed), let me know!
