MSBuild and Jenkins: where to put credentials?

I am trying to set up a small continuous integration server using Jenkins, Git and MSBuild.
I have read so many different tutorials on this topic but I still have so many questions!

I created a Jenkins job which will pull changes from Git and deploy to another server with MSBuild.

The build action is calling MSBuild.exe and takes the following properties:

/p:VisualStudioVersion=12.0
/p:Configuration=Release
/p:Platform="Any CPU"
/p:DeployOnBuild=True
/p:DeployTarget=Test
/p:MsDeployServiceUrl=https://myserver:8172/MsDeploy.axd
/p:AllowUntrustedCertificate=True
/p:UserName=myusername
/p:Password=mypassword

It is working happily, but I would like to know more. For example:

1. I am specifying the credentials as properties. Is there a better way to go? Please note that the deployment server is external (not in LAN)
2. Do I need to use the /P:CreatePackageOnPublish=True property? If yes, why?

Until now I have tried to follow the following tutorials:

• http://www.troyhunt.com/2010/11/you-deploying-it-wrong-teamcity.html
• http://www.infoq.com/articles/MSBuild-1
• http://www.jayway.com/2012/10/17/a-simple-continuous-integration-and-deployment-workflow-with-asp-net-mvc-github-and-jenkins/