All on 4: impression technique and denture fabrication?

Authors

I have a few questions regarding the Nobel Biocare All-on-4:

1) After we convert a denture in the mouth and pick up the temporary cylinders in the denture, is it required to take an open tray impression, as well as provide information on the soft tissues to the lab (for final denture touch up) to make the denture intaglio surface convex?

2)Do you always advise converting the denture or do you also advise sometimes to just take open tray impressions after implant placement and let the lab make the denture from scratch after the implant placements?

3)Is the denture that is suggested, a fibre reinforced flexible denture or just a normal denture? Can a flexible denture be converted? I have my doubts as the acrylic will not adhere to the flexible material during immediate pick-up. That is the reason for the question.