So you don't have to configure anything for this. Whenever you deploy your application it will scan the scheduler class and create an AWS cloudwatch rule for every task. So it basically creates a cronjob for each of them automatically for you.
Like everything else, Vapor takes care of it for you ;)
Normal cloudwatch event limits would apply... probably the most relevant one would be the limit of 100 rules per region per account. That's a soft limit though, you can request an increase if necessary.
That's still probably way more scheduled events than most people will have