G1ANT robot always finishes one action before it starts another one, so you don't have to worry about any PC lags.
Entering your email is required when you haven't yet activated G1ANT.Studio on your computer and it should happen only the first time or when you want to change your license.
Entering license key in order to open the G1ANT editor is required due to security reasons. This way you can make sure that only RPA developers can change your G1ANT code and no one unauthorized who doesn't know the license key can use it. But this feature is only in the production version. Developer version doesn't have this protection.
What do you mean by "proper installer"? G1ANT.Studio is so light (it weighs less than 150 MB) that .msi is not needed, you can just download it from G1ANT website and use it without any installation right away.
The G1ANT editor doesn't have to be opened for the scripts to be run, triggers work correctly if they're activated and G1ANT.Studio is running.