I highly recommend that you go back and play the first game even though the plot was already spoiled for you bc of the anime adaptation. I actually watched the anime too before going into the game and I regretted doing so tbh. the anime just feels like a summary of the game's plot and def not the full experience, there's a lot you're missing on in terms of character development if you don't play the game at all, even if you already know everything that's going to happen storywise.
From what I've seen while the steam port seems nice I think vita would probably be the best way to go. The third game in the series isn't even available on steam anyway and who knows when/if that'll happen. so go for vita since everything's there hah