If any tadpoles DO hatch, you should turn the fountain off until they are quite big as they will probably get sucked into the pump and minced.

I don't think it matters if it sinks. It is only usually near the surface because frogs tend to lay it in shallow water ot on submerged plants.
I expect it would take longer to hatch at depth as the water will be colder there.
Don't give up with the spawn yet.
Make sure yu have lots of oxygenating plants in the pond, and next year you should have frogs find your pond by themselves.
ps Werndal is right about the risks of moving spawn from another pond. If there are diseases in the frog population in the original pond (like red leg disease), then it will be spread to the new pond.