Your husband ultimately has to prove to Immigration Court that his first marriage wasn't fraudulent and USCIS denied his applications based on his first marriage in error. Without this, the new application based on the 2nd marriage is bound to be denied.
There's nothing unusual about this set up, in fact, it's good evidence that she contributes to a joint account which is then used to pay bills! Prove this with documents. Prove it happens every month!
USCIS is fine with it if you re-file. There's no deadline on filing an I-485 after K-1/K-2 entry & marriage (although ideally one does it sooner rather than later).
While the 90-day period expired, a spouse of a USC can file for AOS even with an overstay.
Yes, and unfortunately, it's not moving a month every month or anywhere near that, so you can't just look at the date now, deduct it from the present year and say, I waited x years so far, so that's how many is left......
"a couple months before the divorce was finalized in the US, we got married in a small courthouse type marriage in Syria."
Like I said on Reddit, obviously an invalid marriage as you were not free to marry....