"DoctorUSA" wrote ...
1. What radio should I buy between the two: Yaesu
VX-7R or Kenwood TH-F6A
2. Where should I buy it from (price) or maybe someone
sells one used ?

the first question: I want this radio in order to be able
to monitor (listen) to all possible things: weather, radio,
police chat, trackers, taxi dispatchers an so on.
Also I would like to be able to talk back to some of them
(definitely not a police )

While you may be able to receive most/all of those
sources (because both models have a wide-band
receive function) , it is very unlikely that any of those
services are using ham bands, which would preclude
you from "talking back" to any of them. Also neither
radio will transmit in the bands they are likely to use.
Fortunate for you since is is almost certainly very illegal.

A "scanner" type receiver seems more suitable for
listening to the various services you mention. Particulary
in a large city where they use "trunking" and other
systems for sharing (and jumping around) between
different frequencies. Many scanners are progrmmable
to handle this. But neither of the radios you mentioned
can follow these kinds of conversations.