Reference everything you find interesting about ICU here. All these ICU infos are generally deeply nested into Github issues and not so easy to find, as i18n is generally not a trending topic.
Issues are free to discuss anything (best SaaS supporting ICU, coordinate effort to create better tooling... )
icu-message-format-for-translators
ToolsPortal Message Format editor
TODO
Plural and Gender in translation messages, Google 2012
TODO