hello,
I just did a very similar project using an atmel AT89C52 microcontroller and a 2 lines LCD. it was a tachometer, don't worry its the exact same principle.
So my answer, Yes it is simple IF:
1- you are familiar with C
2- have some basic experience with uC
There is no need for op-amps unless you are going to make a project that measures frequencies on many voltages, if you measure TTL frequencies (pulses of 0 and 5v) you don't need op-amps.
Look i'll be with you from the begining to the end, specially if you use an AT89C52 or similar.
Good luck, its doable, and i'am willing to help!