A: Diameter is the measurement of your propeller from the center of the propeller to the end of your blade x 2. Pitch is the distance the propeller will go in one revolution in air. Example, if you have a 15 pitch prop, it will go 15 inches in one revolution.
A: You may think that a small ‘ding’ or bend will not effect the performance of your boat. In reality, a propeller effects a multitude of things on your boat. If you have an improper balanced or damaged propeller, it can change your RPM’s, gas mileage and in some instances cause damage to your outdrive shaft.
A: It depends on how you use your boat. Generally, going down in Pitch will increase your power but also increases your RPM’s by 200-300 per 2in pitch change.
A: Again, it depends on how you use your boat. If it is for leisurely recreation, than a 3 blade will work just fine. A 3 blade will give you all around performance. A 4 blade will give you increased low to mid range performance but may decrease your top end speed.
A: Aluminum propellers are more affordable to purchase and to repair. If you are a recreational boater an aluminum is a great propeller for all around performance. Although more expensive than aluminum, a stainless steel propeller is the most affordable way to enhance your boats performance. 
A: A Bronze propeller is made up of Bronze metal. A Nibral propeller is comprised of Nickel, Bronze and Aluminum metals and is a more durable propeller. 
A: The propeller is attached to the shaft, the shaft runs from the engine through a seal, then the hull into a bearing then onto the propeller. The propeller shaft must be free of any bends and cracks or it will cause vibration and can erode the bearing and seals.  The shaft is made up of hardened steel, comes in various lengths and diameters. It is tapered at the end(s) with a threaded section where the propeller is attached along with a propnut and a cotter pin to hold it in place
A: All propellers have recommended overhaul intervals based on calendar time and flight hours. Depending on the prop model, the amount of time in service could be 1,500 or 2,000 hours. It is important that calendar time be carefully considered at about 5 years in service.
A: A typical repair to an aluminum prop will cost $100 to $150, but expect to pay $200 to $400 to repair a stainless steel prop. It may be more cost-effective to simply replace a damaged aluminum prop, but when a new stainless prop costs $400 to $700, the repair makes economic sense.
A: The purpose of polishing the propeller is to reduce fouling of the propeller and provide the highest smoothness to the surface of the propeller for reduced drag, faster speeds and higher fuel efficiency. A smooth surface will prevent marine life from attaching itself to the propeller.
A: The trick is to sand your precious prop, and then apply an epoxy tie coat before two or three topcoats of regular bottom paint. I've found this lasts the best part of a season.