Hi Pierre,
This forum is mainly for turbine powered models.
There is a lengthy thread on RCgroups for this model, which will answer all your questions, but here goes as I have one of these and they are a lot of fun to fly:
It's a jet.... its meant to be fast, and trust me, its not actually that fast
1: 80% for low rates and anywhere between 15-25% expo
2: Moving CoG aft will slow approach speeds down a little, but can also make the model very touchy. Practice approaches with the nose up and using throttle to control decent rate. We find the model can land quite slowly for a jet.
3: have you taught the ESC your radio? if not. Radio on, throttle to maximum, power model up, listen for the beeps, pull throttle to the off position, listen for me beeps. ready to go, should have smoother throttle. you should do this with all new electric models
4. Same as the manual states. If it is a windy day I only use part flap. about 15mm downwards
Thanks
dave