Planning Update in P6 vs P3

Hello, i am used to update planning for EPC Projects in P3. I am starting using P6 and i have problem finding good configuration (Calculation rules, user preferences, ...) to get a good result for my progress which is based on actual unit.

I would  like to input a % progress which will calculate the actual unit from the budgeted unit. Remaining unit will be recalculated by Budgeted unit - actual unit. But I would like also that my finish date is defined as an expected finish date (not linked to my % progress).

This method was working well on P3 but apparently it's not possible with P6.

If anyone has an idea feel free ...

Thanks

Cyril