If you (and your son) buy service from a decent ISP, you should be able to play without packet loss. There's nothing special about that. I use a Dutch ISP to play on servers around Europe, and hardly get packet-loss. Between US and EU might be a little bit more troublesome. But there should be ISPs that give you connectivity without any packet-loss.
Ping is depending on a number of variables. Faster Internet is one of them. But only if you have less than 1 Mbps downstream speed. If you're over 1 Mbps, ping will hardly go down if you go from 1Mbps to 10 Mbps. And going from 10 Mbps to 50 or 100Mbps, will make difference at all (maybe a few microseconds. Micro, not milli). If your upstream would be below 500 Kbps (0.5 Mbps) that could be of impact too. But nowadays, everybody get a few Mbps downstream and at least 1 Mbps upstream. So no problem.
The biggest influence is the speed of light. Light is slow. Too slow. And there is nothing anyone can do about it.
Speed of light is 300k km per second. Which is 300km per millisecond. That's through vacuum. Through fiber-glass it's only 0.6 as fast, so ~`180 km per milliseconds.
Most likely there are no cables in a straight line from NL to Florida. So we should assume NL -> New York or Washington -> Florida. That's 6000 + 2000 = 8000 km. Let's give them a little extra, so they can be curved, follow the us coastline, etc. That 9000 km. Ping = Round Trip Time = packet goes back and forth = 2x one-way delay. So for a ping, a packet has to travel 18000 km. That means the speed of light introduces a *minimum* of 100 milliseconds.
Normally when people play on local servers, a ping of 50ms is considered quite good. (Note, different games measure ping differently. So it's hard to talk hard numbers). But what you should consider "good service" would be an in-game ping of 150 ms and zero packet-loss.
There is nothing you can do on your PC or router, or on your son's PC or router. Performance will depend 99% on your ISPs. So the only way to improve performance is to get service from different ISPs.
Maybe one ISP, maybe you need to switch both ISPs. To find out, you need to measure performance a bit better. The normal way to do that is by using "traceroute". Also called "tracert" on Windows. You can find out where the delays are on the path between you and your son. And maybe also where the packetloss is. Based on that info, you maybe can find a better ISP. Google for traceroute to learn more about it.
https://www.google.nl/search?complete=0&ion=0&q=traceroute tutorial
Sorry that I can't give you a registry-setting that would fix all your problems.

Those don't exist.
Good luck.