Not really. When I entered through the border in July the border agent said I will start my 5 year RO period from now.
I wouldn't count on the verbal statement by the border agent. In other words: not technically correct. You may benefit in practice from leniency based, basically, on the previous decision and a new PR card (they tend to treat new PR cards / those with several years left) as effectively showing compliance. And it may not be likely given the decision was rather recent. But it is not a 'start over' as if your first five year period, it remains a rollin
This may be fine for most purposes, esp if trips abroad not long. But if you stay out much longer and/or appear not to be living full-time in Canada, they might look into it in more detail.
Although technically they could at any time, really. That may not be very likely, but I doubt anyone could tell you with certainty.
Up to you. Given the history, I think overall you'd prefer not to have the file re-opened. Chances of issues will go up the more often you pass borders/have significant periods of time abroad. Your choice. I'd note that often a 'flag' of previous non-compliance remains visible to cbsa officers for quite some time (even when circumstances have changed).
Once you do have 730 days + in the relevant period, the issue is resolved though.