White Strength Seal is basically created by storing chakra for a very long time to create the seal, which many people do utilizing other methods anyway. As for the Creation Rebirth, I don't see the point of combining it with Edo Tensei because they function differently. CR causes your cells to replicate alarmingly fast (think Wolverine) while ET turns your body into an ashy/paper kind of material that just materializes any damaged portions. No cells involved.
I figured that the regeneration rate that comes along with being zombie itself could negate that passive ability, since it requires living cells in order to be fully utilized by that individual. Madara displayed the regeneration ability soon after he was revived and never used it as a zombie himself, so that means some restriction still apply whilst being an ET.
Do ET even have living cells technically? Since they don't bleed or anything, I always kind of figured the only 'living' portion of them is the body used as the base and the DNA used to make them. I guess CR wouldn't even work on an ET person...Though I guess if an ET lives long enough, they could use the WSS. At the same time, the meta of this game basically invalidates the need for the WSS because everyone has infinite chakra anyway.
Edo Tensei can still bleed, salivate, secrete bodily fluids and display usage of blood-line limits that make use of living cells. However all of this happens under a certain and sometimes a specific circumstance, for example: As an ET, Itachi's eyes still bleed when he casts Amaterasu. Hanzo the Salamander still had access to a organ that secreted a deadly poison. Houzuki Mangetsu was given access to his blood line limit in the field of combat
(4th Great War) and even displayed using it to drown that unfortunate opponent.
Personally I think you can't even use either one of those passive abilities as an ET, but like you pointed out with the meta these days; it's a broken system of chakra stats. I guess CS can be used as a field advantage to get that person out of a tight situation.