The effect of "Kaiser Sea Horse" does not apply to Ritual Summons.
If "Kaiser Sea Horse" is used as 2 Tributes for a LIGHT monster, the effect or "Precious Cards from Beyond" will trigger.
If "Kaiser Sea Horse" is changed to Dragon-Type before it is used as 2 Tributes for a LIGHT monster, only 1 card will be drawn from that Tribute by the effect of "Super Rejuvenation."