CodePipeline conditionally skip action in pipeline without failing pipeline

We are working on a build once, conditionally deploy, style pipeline. In other words we have a pipeline that has the following make up, for instance:

• Source action - S3SourceAction
• Build & Test action - CodeBuildAction
• Deploy to Dev action - CloudFormationCreateUpdateStackAction
• Deploy to QA action - CloudFormationCreateUpdateStackAction
• Post-Deploy Action - CodeBuildAction

We have multiple repositories that flow through this pipeline. Say for instance I want to:

1. SKIP the "Deploy to QA" action based on an Environment Variable, but still continue to the "Post-Deploy" action.
2. STOP completely, after the Deploy to Dev action but not FAIL the build.

Are either of these possible with CodePipeline / CodeBuild?