If I get those tickets can I visit the Roman Forum before I visit the
Colosseum?
Sorry, I can't swear that you can do that, although some folks have reported being able to get in before their tour times by showing their online reservations. Understand, though, that you can't split up your visits to the Forum+ Palatine. They are essentially a single attraction and you pass from one to the other inside the security perimeter. Once you exit either of them, you can't get in back in.
How strict are they with how early or late we are compared to the time
that we booked our ticket for?
I would arrive 15-20 minutes or so before your scheduled tour to find your gate and pass through the security checkpoint. As stated on the website, delays can occur even for pre-booked visitors if they are very busy (which they will be). Do not miss your scheduled time slot!
...do you get notified that I tagged you?
Nope. I opted out of notifications and just check my forum history regularly for most recent activity on threads I've participated in.