While we cannot address all these questions here, let me get you started. If an invention is going to make money, it must be more than just a good idea. Store shelves are already filled to capacity, so a new product must be outstanding to attract customer's attention. Watchdog agencies like the U. S. Food and Drug Administration, OSHA, and the Underwriter's Laboratory are watching to make sure any new product conforms to local, state, and federal laws. Does your product have safety concerns?
Know your potential customers. Is the market for your product growing or shrinking. A few years ago a lady started mixing flour and clear finger nail polish. Four years later she sold that company to the Gillette company for $42 Million dollars. Today the market for Liquid Paper or White Out is shrinking, not growing.
Do you need a Patent? Many people waste time and money pursuing a patent, convinced that if they can get a patent, they will be rich. No, you can get a patent on anything that has not be patented before. Thus, you could get a patent on square wooden wheels, but I doubt that anyone would want to BUY them. A patent here does not protect you from someone in Taiwan duplicating what you have done and selling it here. Many times it is wiser to spend your time developing your MARKETING plan rather than protecting your idea.
Be careful of Independent Product Developers (IDPs) Many will lead you down the rosy red path telling you your idea is the greatest thing since peanut butter when all they are doing is extracting your dollars.