Sarang&Anjie

Meet in Canada or Mexico if it’s any easier for him to get a visa for a third country 

I don't mean to sound insensitive.  My wife and I were married in Taipei in mid 2015, and we resided there.  In 2016, we decided to relocate back to the US.  We were apart for 13 months......I know your agony........Thank goodness for modern video calling....

He can apply for a B2.......but it is not likely.  With no ESTA and no B2, there is no other way........separation is an unfortunate part of the process......and most of us have had to endure it.   Sorry.

If your residence is US.. or going to be when you return ... file any time you want and use your US residential address on the 130. It’s not the length of absence that is the issue .. it’s the intent .. temporary or permanent. Om assuming you are in Australia on a working visitor visa.. so you are not a permanent resident of Australia 
You do not need to stay with him.,  visiting is fine .. you will need to demonstrate US domicile and either meet the financial support guidelines or have a joint sponsor. 

Yes, someone else can pay for it, the cardholder must complete that G-1450 form ,sign it and give it to you to submit with your filing.

Yes, but it is also CRITICAL to carefully study I-130 and I-130a instructions, and become an A-student of them.

From your questions, it sounds like you need to do a lot more research before you file the petition.  Read the guides, search the threads, read and study everything carefully, collect evidence, gather documents, then submit the petition when everything is ready to go.  Don't rush the petition or you may not include enough evidence of a bona fide marriage relationship.  Also do more research on visiting during the one-year visa process, establishing US domicile, etc.  Good luck!

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