It's been a while since I've flown a Standard transborder fare, and trying to figure out how seat selection charges work, as well as what happens in terms of changes. Ditto if I get a pre-pad meal voucher.

Seems like both of these fees are mostly non-refundable, save for IRROPs. Can someone please explain to me what happens if:

• I pay seat selection fee, and/or meal voucher, then need to [voluntarily] cancel my flight? I know the credit for fare would be non-transferable, minus the change fee, and goes into my AC wallet. What happens to seat fee? Seems that remains non-refundable but per site, value remains available to me to use later for seat selection [only?] - where does it go and how do I use it? What about meal voucher...is that lost or is that still available to me on a future flight?
• What happens if I book a standard seat now, then decide I want to move seats?
  • Let's say I decide to take one of the lower cost standard seats (ie, behind exit row in 7M8), but decide I want to 'upgrade' to a forward row standard seat that costs more, or a preferred seat. Will I be able to pay the difference, or do they charge me the full amount of the new seat. If the latter, am I then able to apply for a refund of the original seat?
  • What if I want to change to a different standard seat that's the same price, am I able to do that without additional charge?
  • What if I decide to do an upgrade bid and get it (unlikely, but who knows?). Is there an ability to request a refund in that case (I don't see any terms addressing this, so I'd guess no, but just trying to see if there is any real-world examples).
• What if I want to change my seat at check-in - seems AC was for a time charging for seat selection at check-in, then rolled that back? If this is still the case, say I paid for an aisle seat in, say, row 25, but see an aisle in row 10 is still open - can I do that (I'd presume no refund/credit on original fee paid).
• I assume if there are IRROPS, and get put on a different flight, in particular, a UA flight (though I guessing AC prefers not to do that, even intra-alliance), I could request a refund of both seat selection and meal voucher fees?

On another note, does it make a difference if I book the seat selection at booking, or book fare first, then go back in and select a seat later (aside from availability differences)? Not 100% sure, but seems the seat fees are pretty standard by route/type, and not subject to demand-based price changes?