General questions on Timers [STM32 & CubeMx]
Regarding the AHB/APB question, this is best explained with a look at the Clock Tree.
AHB and APB are not the same bus. The AHB has memory and core, the APB has peripherals. Energy wise these might not have the same speed.



A special case in ST chips is that the peripherals, including the timers registers, are clocked at PCLK1 and the Timer clock source is on a multiple of PCLK1. This allows slower APB1, but still allows faster timers.


  Does this say the period in milliseconds?


It gives the result in timer ticks.


  The TIMxCLK frequency is set to 72 MHz, the prescaler is 0x0 so the TIM2 counter clock frequency is 72 MHz. So the minimum frequency value to measure is 1100 Hz.


How do I calculate that minimun frequency?

Clock / Timer maximum = 72 MHz / (2^16) = 1.09863281 kilohertz.


  How do I choose the prescaler and counter period effectively in CubeMx according to my frequencies range?


You probably can't use one range if you need a large capture range. You could switch the prescalers automatically, like your multimeter does in Auto-ranging.