The first sentence is global, in general is good to workout, while the second is specific to the persons. You talk that you and someone else (or several persons) have to workout. The people are integrated in the second sentence which lead to feel more concern about it.
The right writing is: “il faut que l’on fasse de l’exercice tous les jours”
For the last three ones, the meaning is similar but the importance of the task is different.

“Il faut qu’on fasse” only concerns the people referred to by the “on” : “We have to workout everyday“.

“Il faut faire” is more general, it doesn’t apply only to a group of people : “One should workout everyday (to stay in health, …)“.

Note that you can also use the general statement and apply it to a group of people : if it’s recommended for everyone, it also applies to us.