If autopilot is on, should PF inform PNF about actions on FCU (ALT 5000 pulled, NAV is managed,...)? Or just read FMA and be happy?
Generally just read the FMA's
A lot of times FCU adjustments will be as a result of an ATC clearance so there is no need to discuss it. If you are going to do something that you think the PNF may not be expecting you could state your intentions if it is not obvious so that they are "in the loop"
During NPA should PNF narrate all the calculation process at altitude check waypoints (approaching distance 10 DME, alt must be 5000, we seems to have 5200, so we 200 feet high, ....)? Or just call out 200 feet high and be happy?
The PF should brief the PNF on what calls they'd like.
Generally at about 0.5 mile before I'd say "at 4 miles you should be 1560ft" then on passing 4 miles I'd just say "on profile" or "50ft high" etc
SW