Yes, the added zeros are significant. Lets say you are converting 1.23 x 10 to the power of 4. The answer would be 12,300 in which case, if you took away the zeros, the number would be 123, which is an incorrect answer.
Hope this makes sense and helps!
Tough call.
You may have to use Newton's Method or something like that.
Graph y=2^x and then graph n/x on the same set of axes. You may have to assign some arbitrary value to n to make this work. From the graph you can read off the approximate coordinates of the point of intersection.
The percentage would be 51% but if you want to round it the answer is 50%