In the original series, Raia did have the Survive Shippou. Ren/Knight inherited it because Raia gave it to him, just before he died from Asakura/Ohja's Final Vent. I forgot which episode that was.
Shinji got his Survive Rekka from Kanzaki. It was never really explained why Kanzaki wanted Shinji to have the card. My own personal theory is that Kanzaki gave Shinji the Survive card because he knew that Shinji protected Yui, and there is a chance that Shinji (if he is the Final Rider and fights Odin) would intentionally lose to Odin and give up his life to save Yui's. Also, I think Kanzaki wants someone to balance out Ren's power (since he has the second Survive card).
As far as the RPG goes, I'm not going to use the Survive card very often, for a couple of reasons:
a) We don't know much about Raia's Survive Advent cards, and I don't want to catch people by surprise. As far as his Survive Form goes, I will try to stick to abilities Raia already has.
I'll add maybe one ability that Knight Survive Form has. Shoot Vent is the likely candidate here since Raia Survive's Rider Visor, which I'll call "ExoVisor" (since EvilDiver becomes ExoDiver in the picture), looks a lot like an English Longbow. Just take a look at the picture I attached in the bio for Takano. So it seems to make sense to have Raia Survive shoot arrows. Everything else stays the same, even his Final Vent; they'll just have slightly higher attack points.
b) Takano more concerned with finding his brother than the Rider War, so he's not going to use Survive Form to actively kill others. It only makes sense for him to use his Survive card if he's in a life-threatening situation, as a way of self-defense. He may also use it if he needs to protect someone and Raia's basic powers aren't enough.