Setting Up Hreflang and not getting return tag errors

[cian_murphy]

I've set up a dummy domain (Not SEO'd I know) in order to get some input on if I'm doing this correctly.

Here's my option on the set up and https://technicalseo.com/seo-tools/hreflang/ is saying it's all good. I'm self-referencing, there's a canonical, and there is return tags.

https://topskiphire.com - US & International English Speaking Version

https://topskiphire.com/au/ - English language in Australia

The Australian version is on a subdirectory. We want it this way so we get full value of our domain and so we can expand into other countries eventually e.g. UK.

Q1. Should I be self-referencing or should I have only a canonical for US site?

Q2. Should I be using x-default if we're only in the English language?

Q3. We previously failed when we had errors come back saying 'return tags not found' on a separate site even though the tags were on both sites. Was this because our previous site was only new and Google didn't rank it as often as our main domain.

[cian_murphy]

Should I remove the og:locale in Yoast that for some reason references 'en_US'. I'm using Wordpres multisite so I think it pulls the default language  in the plugin even though 'en_AU' is in the head of the AU site.

[Martijn_Scheijbeler]

Yes, in your HREF Lang tags you're always self referencing them as well.