"Elemental HERO Neos" and all Fusion Monsters that list "Elemental HERO Neos" as a Fusion Material Monster gain 500 ATK. Fusion Monsters that list "Elemental HERO Neos" as a Fusion Material Monster do not have to activate their effects during the End Phase that shuffle them into the Extra Deck.
We're yet to get a skill that starts with a Field Spell with that high of a boost on the field. I'd imagine if we got a Neo Space skill, it would probably either be like the HHG skill (and put it on top rather than activate it), or a lost-LP one. It probably wouldn't matter either way, but it would be inconsistent with how they've done it so far.