How many fps do I gain when I had 5 pounds of draw? I know there are many variables, but whats the general rule?

Usually about 2 fps per pound of weight.

that 2 feet per second may vary depending on cam design, axle to axle and Brace heighth. but ingeneral 2 to 4 feet per second. for each inch of added draw lengthyou can expect at least 11 feet per second increase in speed.