Older versions of add-ons are available on https://marketplace.atlassian.com
JIRA Agile in particular can be found here.
Download the most recent available version for your version of JIRA and use the Installing by file upload method to get it up and running on your instance.
This should cover all 3 of your questions
In the past, Portfolio for Jira required a high degree of detail–foresight that was unrealistic for many businesses to have–in order to produce a reliable long-term roadmap. We're tur...
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