Red tailed sharks are asses and will eventually bully everyone in the tank, including the angels.
As for the Krib, a lot would depend on its personality, but it would probably be fine with the angels. If you notice aggression(once it matures), you can return it.
I think the domesticated angels would be fine with PH of 8, the wild caught one's not so much so.
I am not a fan of using methods to bring down the PH as it usually backfires in the long run.