As regards your first question, none of the 2E material is official in 3E unless your GM approves it or it showed up in 3E material. The current (as of late 2016) live developer made the following comment regarding someone asking after Battle Form in Mecha and Manga:
Many of the genre-specific powers and rules will only pop up again if we do an update of the supplement or make a different supplement that covers similar genres. For now, lot of the powers from Mecha & Manga and other 2e supplements can already be built with the 3e rules. Battle Form is simple a set of powers that has the activation flaw. If you want to keep with the original power's "you can only maintain the form for one round per rank" limitation, that's a GM call as far as the flaw value, but 4pp per 5 points to build your battle form seems appropriate (similar to how the Removable flaw works; both limit the availability of your power).
Ultimately, if you want to play 2E, those books will set you up nicely. If you want to play 3E, you will need to either buy the sourcebook or make use of the SRD. As noted by Jeff, there is a conversion guide from 2E to 3E, so you can probably convert characters over, but the mechanics and costs are different in several places.
Personally, I primarily play 2E, as I feel it's the more mature product (and has a lot more official clarification that 3E never brought over), but I've come to accept 3E as a valid system and I play the occasional game in that too.
Either way, I highly recommend dropping by the official Green Ronin forums or one of the unofficial sites to find people to talk with and play with.