Firstly, how are you going to get +/- 0.1hz resolution with only 4 digits to display at 10mhz??

There have been other posts regarding frequency counting and there are plenty of examples on the web.

If you want speed and accuracy at low frequencies, you would normally use a reciprocal method: measure the period then convert to frequency = 1/period.

For the higher frequencies, the circuits I've seen use a /16 counter and the internal counter/timers. I can't see why you need a pll or three counters.