Hello,
In regards to Ashura, rest assured that his price will drop as time goes on.
In regards to the seal scroll drawings and recruitment, I can make that suggestion for you, but I'm pretty sure that the game will not deviate from the Chinese version in that regard, so what seal scroll treasures we will get will not likely change in that nature.
In regards to SSP Naruto, his price has actually already dropped substantially from his original release price (to something like 60% of his original price). He's also already a pretty frequent ninja in events, to the point that many players complain about him being pretty frequent, so I'm not sure how much more frequently he could be present in events.

Thanks, and hope this helps!

Naruto 6paths is in fateful choice right now (and was in fateful choice just a couple weeks ago). Kakuzu Grudge is in events almost every week. He is in the event with possible discount cards of 10%,20%,or 50% right now for 165 for each frag. It is a box with a choice between Kakuzu grudge or Deidara edo. With a 50% card you could get grudge from no frags to 4* for less than 15k.