That is not a firmware issue. I use -25 ms both with FW2 and FW3. The offset you need to set depends on your location in relation to the servers and (maybe) a little due to server load at peak times. I assume that TheHandy use Amazon, Google or Azure as their cloud provider and they support having data centers in North America, EU and Asia/Pacific (and other locations) to minimize the latency for most users. If they have one in all regions I don’t know. If you want to get a feeling for latency to data centers then you can check the Amazon AWS latency monitor.
That is true IMO. It’s because FW3 has a softer direction change (starts slowing down a bit earlier than FW2). The strokes are not shorter afaik.