It's currently unknown how many cards the full set will contain
However, in general, I tend to disagree with the first and second reasons
While the main series often sticks to, though improving on, the idea of having the player travel around their respective region, gathering Gym Badges, levelling up their Pokemon and generally end up saving the world and becoming champion, that hasnt stopped them from branching out into a whole slew of other subseries
Veteran Magic players ought to be thrilled to see the return of familiar characters such as the artificer Tezzeret, alongside creature types like Kavu, Slivers, and the ancient Eldrazi
First strike on a double-striking creature is redundant and doesn't change the creature's double strike ability
The second mode affects only creatures you control at the time it resolves