First Question: Unsure with real device but in simulator, upon test completion the simulator is cleaned and WDA is uninstalled so it must be reinstalled when initiating a new test.
Second Question:
Including this should solve that:
capabilities.SetCapability(“xcodeConfigFile”, "/path/to/file.xcconfig); // This config file manages the code signing for WebDriverAgent
The .xcconfig file should contain the following:
DEVELOPMENT_TEAM = [TeamID]
CODE_SIGN_IDENTITY = iPhone Developer
Your team ID can be found here after logging in.
Third Question: Solution for question 2 should solve this as well because it will use the config file to get the signing identity.