This is what's called a 4th order , box . One sealed side ,an o e ported side enclosed, or walled off . Hint inside of a vehicle , with the opening tuned to a different port tuning than the one inside the box.
3/4 MDF with reenforced edges would be the preferred sub box building option. Plywood will eventually rattle like crazy, especially if not glued and supported with brackets. Also, any open ends or sides with airflow should be curved. There is no one size fits all. The subwoofer will dictate the dimensions of the box and preferred sound/space will dictate vented/ported or sealed.
Totally disagree to your opinion. Plywood are much stronger than MDF, MDF will not last longer when it got wet even if it has paint on it because of the moisture
Also disagree MDF is not the end all wood to use. Plywood, birch are also other options to use with fine results. And prob 99% people can't even hear a difference in wood used
