Osburn insert hearth size

Finally my stove is on its way but not before we had a $400 propane bill for one month of heating a 1,500 sf house! So outrageous. We have to build a new hearth. The stove is a Osburn 1800 insert going into a cheap metal fireplace. I am assuming the new hearth will have to be built up several inches high. The stove will stick out a few inches but how much beyond the stove is recommended for the hearth. The fireplace has a a metal lip on the top and the bottom in the front. Will those have to be removed as well? thank you to everyone that has helped me with my stove research since May as I am soon to be apart of the woodburning community and could not have done it without you folks. d

Warren I was looking at some pictures you posted of your Osburn 1800. The finished project pic is too small to tell but it looks to me like your hearth is flush with the floor. Is that correct, Not sure where I got the impression the hearth had to be built up higher. Also in one of your bigger pictures of the fireplace before installation of Osburn you have a piece of cement board cut to fit the floor of the fireplace....I dont understand why this is needed. Could you explain please. d