Let's make sure that we can not just keep adding to the existing power source. Adding outlets, lights, disposals, etc. will only put a greater burdan on the electrical supply. This means tripping breakers, and even electrical fires. You do not want to add to what you have without increasing the power supply.
It would probably be best to contact a qualified electrician to upgrade your electrical supply to the building so that you can adequately make inprovements to your property. Put together a list of what kind of improvements you would like and discuss these with the contractor for his professional opinion. Many contractors will be more than happy to meet with a property owner that is sincere about doing some improvements to their building.
Good luck in all your home projects.