A year is NO time at all, no offence but at 29 it may seem a long time, it really isn't. ESPECIALLY when moving in could compromise you financially as well as emotionally, AND when there's children involved.
Also you say he'd have given his marriage a chance if possible - he barely gave it OR parenting really, a chance at all.
Working with someone, even dating them is nothing like living with them. He's not even divorced yet. Seriously you need to slow down.
No they haven't 'adapted' they're too young to understand what's going on! It's when children get older the problems become apparent. My dd was 2 when ex and I split and was fine initially, as she grew (and admittedly no thanks to ex playing silly buggers over contact) and realised she didn't get to live with her dad or even see him much, that he'd moved on and had a new family and each new child he and 2nd wife had, impacted on her in a hugely negative way.
Besides which - how the hell would YOU know? You don't know them and you don't know what it's like parenting at all.
Have to say I too am sceptical you had no part to play in the breakdown of the marriage and would be thinking that if I were his ex.
"He's a great dad" based on what?! He's barely been a dad at all - you don't have DC yourself, being a great dad means:
Making more than a passing effort to maintain the marriage
Not running off at the most difficult point of parenting (arguably, but certainly I bet he thought so as he hasn't yet parented teens)
'More than most to support his family' - do you mean financially? Because parenting is about much more than 'throwing money at the problem'
If you move in after just a year of dating you ARE rushing things.
Most people I know even in their first serious relationship didn't move in until they'd been together at least 2 years, usually 3-4.
You sound incredibly naive and somewhat immature - even given your age.