Green Ronin Fantasy Age 2nd edition: some questions about Specializations

[Strider1973]

Hi everybody, I just bought the pdf of the Fantasy Age 2nd edition Core Rulebook and I'm enjoying a lot, I've got some questions about Specializations in the game.
Particularly:

• Do you have to "complete" all the three levels of a Specialization /Novice, Expert and Master) before beginning a new one, as it was in Fantasy Age First Edition, or not, and theoretically you can just begin a new specialization every three levels, provided that it is allowed to your classe and that you meet the specific prerequisites? I can't see a clear rule about this in the Core Rulebook: am I missing something?
• In the Fantasy Age Companion for Fantasy Age First Edition there were some specializations that have not been included in the Core Rulebook for 2nd edition, for instance the Beast Master. Some other Specialization have seen their talents changed (ii.e. see the Master Feature of the Paladin in 1st edition Fantasy Age Companion and the Master Feature of the Holy Warrior - the new name for the Paladin - in 2nd edition Fantasy Age Core Rulebook). Can the 1st edition Fantasy Age Companion Specializations and their powers be used, with the GM approval, of course, or are they considered too powerful?

Many thanks and happy summer!