Meshtastic

Yeah, when i look at meshmap.net i often see that called "root topic". I don't know much about MQTTTT. So, when I hear server, I think of like example.com and i dont see anything like that. I know MQTT bridges the nodes to the internet and there's something about uplink and downlink and I understand the uplink to allow data from your mesh to go to the internet. But is that just to allow different networks to talk with each other over the internet instead of RF? Also, what if you wanted to bridge together two networks that were using different modem settings? So like, city A is using long fast and city B is using short turbo. Is it possible to bridge those together? And final thing, I know that the default hop count is set to three, and that you should not exceed it unless you have a good reason to. But based on what I understand, that means that your message might not actually get to your recipient. If they are more than three hops away, would you even see nodes more than 3 hops away from yourself?