I have not seen answers to this yet, but, my guesses:
1) the Ranked cards say "When you have 5 mana" which leads me to think that yes, when you use coin and have 5 mana the cards will upgrade. I'm guessing Druid/Shaman with Lightning Bloom have an advantage there.
2) Battlecries just check for current conditions and then trigger their effect, even if circumstances afterwards change. Cards that trigger with a Battlecry wehn you go below a certain health point, stay the way they were played even if you heal back afterwards. So yes, I think it probably works that if you empty your deck, play Neeru, you get the portal and if you then fill your deck again, the portal will still remain.
Again, not seen answers to this yet, but these seem reasonable enough deductions.
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