Q1: Source test mode
I don’t know - all enabled sources can be tested individually.
Kill phone app
I guess it frees the phone app sooner so you can make calls even if someone is calling you continuously.
Q2: GUI
You only need the GUI to make changes.
If Phonehook is misbehaving do
pkill phonehook
sleep 2
phonehook&
Starting the GUI this way all the time doesn’t do any harm.
The Webview dependency is the problem for 4.6 and 5. Pemek’s version solves this for 64-bit.