1. Any image on any site can be used as editorial. Why wouldn't they?

2. It depends purely on what price the buyer has negotiated with Alamy, persumably by bulk deals. We very, very seldom get the amount which shows on the image calculator, usually much less.

3. Payment is automatic at the beginning of the month after you earn $50, though it can take a few days for it to hit your bank account. E.g. my payment for April went out of my Alamy a/c on Tuesday but just got into my bank account this morning. That's pretty normal.

NB it can be months between having a sale reported and getting the cash. You have to check in your account balance to see if the sale has cleared. If it hasn't cleared within 3 or 4 months, contact CR, or six months for a distributor sale. Sometimes newspaper sales also take six months, depending on where the sale came on their reporting/paying cycle. Contributors don't like this, but it is a way Alamy stands out from the micros, and suits some companies' payment policies/cycles.

For refunds, I have to say I've (so far) only had one which wasn't rebought*, though others may have a different experience. Sometimes they are rebought for less (maybe they negotiated a bulk discount), sometimes more (maybe they bought fewer than they thought they would, or ...?). If the difference is small, it's just a currency conversion rates thing.
*Plus one where an image was bought twice, one for a cover, and one for the inside and the dates were very specific. They were both refunded then one was bought for an inside use only, for a price between the two original prices but for a later date, and I assume that was an editorial change of direction.

I don't think it's necessarily unfair, any more than physical goods can be returned to a store, although there is always the issue of 'did they use it anyway**?'. RM helps with that to a limited degree; RF all bets are off.

**In the pre-internet days, one of our big chains had a relatively liberal returns policy, which many people liked; but it was abused by some, who would buy an outfit for an occasion, wear it with the labels tucked in then return them for a refund. Probably still happens. But then someone on here a few years back said he gets outfits for models for shoots then returns them for a refund and got about as many thumbs up on here as thumbs down (there were downvotes on msg at that time).