Mike,
You don't need to change anything in the Preferences to get the best out of RadarBox. I tend to have "Draw Path Vector" unticked, "Seconds to remove trail" set at 150 and "Network labels followed by *" ticked. I don't bother with "Show Lines to/From".
In the RadarBox section, I have "Download Aircraft Photo" and "Download 2 photos" oth ticked.
By the way, I'm getting between 20 and 30 flights in MyLog with an external antenna at the moment and only about half of those have the "Globe" to show that they will appear on the map - so you're not doing too bad :-)
The higher you can get the antenna, the better. However, a high antenna with a lot of cable can give a worse picture due to losses in the cable!