90 day reporting cycle has nothing to do with extension period for visa. 90 doesn't go into 365 or 366! Renewing a visa extension doesn't do your report.
It's going to be difficult to stay long term. Probably just come on a regular 60+30 tourist visa and look to get an Education visa after you arrive. Are you planning on working?
Have her go to her bank and pay it into her account. It may take a while to clear, maybe months, if you sent a $US dollar money order. It's called a "bill for collection" in Australia. Never send money orders in a currency other than the destination local currency. You can send a "draft" which is a money order drawn on a Thai Bank.
Sorry, but they were just witnessing a Stat Dec and you needed to sign it in front of them. No witness to a Stat Dec needs to verify its content. It's up to the person signing to make a truthful statement.