It's not just you, Banana. I seem to get plenty of frogs mating in my pond every year, but very little frogspawn since our first year here, almost 7 years ago, when we had a huge quantity of spawn and thousands of hatched tadpoles later. Since then, there's been very little evidence of spawn, though I haven't interfered with the pond at all. Perhaps nature is readjusting the local population.
As for the dead frog, I've also had a number of thes, both in and out of the water. I think many of the males simply die naturally soon after mating - or perhaps the females after spawning. I don't think the cycle is affected in any way by cats, which will happily lean over and paw the water sometimes when they see movement, but they can't do much else.