It was mention on here recently (so take it for what it's worth), that with the transfer window open, the squads aren't limited to their 25 named squad (they get to submit a new 25 squad after the window closes to fit in new purchases). With a new manager, there's a chance Cardiff might have...
I believe loan fees are becoming more common. I don't know if they're paying £1.5m, but paying something on top of wages isn't actually so unlikely these days.