Hey Francisco,
Regarding your questions:
1) If I disable Console Logging... does this mean that if I connect a PC to the Console Port I will not see any logging message? - Yes.
2) If I disable Monitor Logging.... does this mean that with a Telnet/SSH connection if I turn on "terminal monitor" on I will not see logging messages? - Yes.
What are possible negative impacts if I disable them? - There are no negative impacts as long as you have syslog messages sent to your syslog server to check whenever required.
HTH.
Regards,
RS.