Calculate A(N) / B(N) with C(N) digits
Pyth, 60 57 58 bytes

.[K`.Rchu,eGsGQjT7e.ftPZQ)Je/u+/*GHhyHy^TQr^T3ZZT\0+xK\.hJ


Test harness

It's pretty straightforward - calculate pi, the fibonacci series and the composites, round to C(n) digits, pad to C(n) digits plus the location of the decimal point digits, done.

A(n): hu,eGsGQjT7

B(n): e.ftPZQ)

C(n): e/u+/*GHhyHy^TQr99ZZT

60 -> 57: Cleaned up the n = 1 special case in the pi calculation.

57 -> 58: Wasn't using high enough precsion for pi for the entire input range - increased 99 iterations to 1000 iterations.

Note on rounding: This uses Python's "nearest even" rounding system, rather than the OP specified "towards infinity" system. However, the difference only matters if the digits immediately following the rounding point are 5000..., e.g. 1.25 rounded to 1 digit. I checked the input range, and this never happens, so the correct result is alway returned.