I set up 8 accounts to begin with using http://www.fakemailgenerator.com, the verification email will be send to that page aswell. You can open it using pdf reader and verify your PTC account. After setting them up and adding them to 1.8.0. (Refresh button to get them confirmed) the map didnt show pokemon..only the red circles. After changing setting to low and restarting app it still didnt work. Then i tried logging in with one of the accounts on pokemon go and completed the tutorial. After the nickname was accepted i exit pokemon go and tried alpha scan again and 2 pokemon showed up on the map. I repeated the same thing with the next account.. complete tutorial..nickname..leave app and try alpha again..and 4 or 5 pokemon showed up.😀 I have done the tutorial with 5 accounts so far and after each 1 i did the same test and each time more pokemon were added to the map.. the scan is showing around 15 pokemon atm. So i think you have to complete the pokemon go toturial with each account you added to alpha to activate them on the scanner.. atleast that seems to works for me. Im going for 10 total and will continue to test after each completed tutorial.
No, it dims your screen and shifts the color to something more orange/red so it's easier on the eyes.
I suggest f.lux for this purpose though (if your phone is rooted) since it will turn off if such a screen (where you have to click install) is detected.
There is an app which does what you described as "awesome" called Go Extender. It detects when your phone is in your pocket or just upside down (can be configured to your liking) and then turns off the screen while the game is still running.
Hope that answered your questions ;)