AWS SDKs are used to interact with AWS services programmatically. There are SDKs available for programming languages such as Java, .Net, Node.js. PHP, Python, Ruby, Browser, Go, and C++. 

We uploaded our CloudFormation template to S3 and provided the location using --template-url. You can also specify the template contents directly or from a file using file:// with another option --template-body.

We created our roles for Lambda manually. If we are using Management console, we can create custom Lambda roles from within our Lambda create function page, or directly from IAM. 

We used one new intrinsic function in our CloudFormation template, Fn::Sub. Fn::Sub, which substitutes variables in an input string with values that you specify. We used it to substitute the AWS Account ID and a few other values rather than hard-coding them.

We also used the following pseudo-parameters: AWS::AccountId, AWS::Partition, and AWS::Region, which represents the current account ID, partition, and region respectively. For most regions, the partition is aws. For resources in other partitions, the partition is named as aws-partitionn (for instance, aws-cn for China and aws-us-gov for the AWS GovCloud (US) region). Using pseudo-parameters lets us avoid worrying about the actual partition name.