Finally got a 2007 Prius after 9 yrs, 3 mo on PC

Switching to Hybrid mode fixes the screen off problem when the ICE shuts down, which I'm sure you've discovered by now.

I've found the most useful XGauge to be the traction battery current meter, listed as BTA. It shows you how many amps you are pulling from the battery, and how many you are putting in during regenerative braking. How much power you can pull from the battery varies based on SoC, mine is around 50~ when in the green zone, 35-40 when at the top of the blue, and it drops quite a bit when the SoC drops any further. Using the BTA XGauge, I've been able to modulate braking to maximize regenerative braking without touching the friction brakes, stay in electric mode for longer glides without the ICE coming on, etc. I 'learned' to drive a Prius on a relative's 2014 model, with the HSI bar. Since the GenII has no HSI bar, I've found this to be the biggest help.