2. How to level off in a low level alt during GA? When not reaching the thrust reduction alt according fmgc, LVR CLIMB will blink when at alt* right?
Be carefull here! LVR CLB is a reminder not an order... You might want to keep TOGA for a bit longer sometimes:
ALT* engagement is based on instantaneous vertical speed and the capture/alt acquire trajectory does not take into account the subsequent reduction of thrust to CLB and possible eng fail after ALT* engagement. In other words: once ALT* engages it draws the capture and does not adapt it to a change in aircraft performance/config.
You could find yourself in ALT* with a relatively high V/S and the a/c decelerating.
So sometimes you might want to keep TOGA for a bit longer. In addition if you pull the altitude again whilst in ALT* it will recompute the capture based on the new a/c performance/config.
A bit off-topic here but a nice side note is that due to the ALT* logic we are reminded to retract the speedbrakes before ALT* engages in EMER DES: the capture algorhytm cannot deal with a change in a/c config/performance whilst in alt acquire.