Welcome to TMP. The only mods allowed are those that are approved by TMP. Other mods are not allowed. You can search the forum to find the thread which mentions which mods are allowed.
In MP, all AI traffic is removed. All you see is other players. If you have offenses enabled, you will be fined for violating traffic rules. Most players disable violations. To me, they are a pain in the behind and a waste of time.
"v" will key your microphone so you can talk through the CB.
I'm sure others will chime in with more tips for you. This is a very helpful group.