If you are using Robot Manager;

1. https://community.pega.com/knowledgebase/articles/robotic-processing-automation-scheduling-service
2. See below.

If you are not using Robot Manager;

1. I would use Task Scheduler to kick off the robot at a specific time as well as some code internally to your project that shuts it down when finished or at a specific time.
   1. Check between each work item so you don't shut down in the middle of anything.
   2. I have the code for the bat file I'd use to start Runtime below.
2. I prefer to store credentials using the CredentialStore component (available in the Advanced tab of the Toolbox). I then create a small project to write these credentials into the machine. This makes the setting of the credentials a setup task separate from implementation of the robot (i.e. the robot just expects the credentials to be there).

BAT File to Start Runtime

C:
CD\
CD "Program Files (x86)\OpenSpan\OpenSpan Runtime"
REM CD "C:\Program Files (x86)\OpenSpan\OpenSpan Studio for Microsoft Visual Studio 2015"
START ShutdownRuntime.exe
TASKKILL /IM OpenSpan.Runtime.exe /F
SLEEP 10
EXEC OpenSpan.Runtime.exe project="path to project.OpenSpan"
EXIT