Core decks vs extensive reading

(1)  Adding easy vocabulary.  There's no one size answer.  If you add them and press 4-easy every time, you will rarely see them after the first few reviews.  This will assure you shouldn't forget them after not seeing them for a while.  If you plan to continue graded readers and such, you would probably see the words often enough that you won't forget them if you suspend them in anki.  I'd say you likely have a better feel for if you need to have those words in anki than anybody else.

(2)  Recognition only.  I'm not sure what you are asking, but when I hear recognition only, I assume kanji word on front, furigana and english translation on back and you are testing for both reading and meaning.  I'm convinced this works best for me, but others seem to like sentences on the front for context.  There are variations where you can have the audio on the front too, but then you don't get to practice remembering the reading.  However having audio on the front makes reviewing the cards much faster.  

(3)  Managing reviews.  I target a specific accuracy rate and adjust anki to allow me to hit that percentage.  Add more learning steps if your learning percentage is low, lower your starting ease if your young and mature accuracy is too low.  Around 75% accuracy is the most efficient, but that demoralizes me, so I aim for slightly over 80%.

If your goal is watching anime and reading visual novels, I suggest doing core 2k and then pulling vocabulary from anime subs and visual novels.  Core 2k has most of the true core(multi purpose) words you'll find everywhere.  There are a lot of words in core 6k & 10k that you will rarely encounter in anime, so no need to spend time learning them.  But there are a lot of words that are common in anime which aren't in core at all.  Better to learn the words you'll need.