The whistle sounds like a little trash in the orifice, it's tiny hole. Most of the time it can be removed from the tubing and use a small wire to clean it out. A pack of orifice cleaners can be found in the welding section of hardware and home improvement stores. You don't want to open the hole up anymore than it is now.

Propane smell is a leak. A loose fitting, bad gasket or O ring. Mix some dish soap and water on the thick side. Turn the gas on, place a finger on the orifice. Use a small brush or drip some soap on all the fittings. Watch for bubbles.