Spawn is very sensitive: you need to move it fast, with the minimum of temperature change (transporting it in large container of water will help), ideally with a good clump of oxygenating weed in it - as the water warms in transit, it also loses oxygen. Do it on a cool, cloudy day if possible. You did the right thing letting it adjust to the temperature of the water, but if it was DOA, then you'll need to try again next year.
The best bet is to find a nearby garden with a good frog population and talk to them about using some, to cut down on the travel time.
If you have fish, you need to make sure that the tads have plenty of places to hide: thick clumps of the oxygenating weed Elodea are great and you can also make little holes in pots and put them in the pond so that their lip is above the water to make refuges for them.
Tadpoles are good at hiding: you never know, some might have made it.
A cautionary tale: http://news.bbc.co.uk/nolpda/ukfs_news/hi/newsid_7282000/7282649.stm
Personally, I think that the more frogs there are, the better.
Bees are active all year round, they just tend to hang out in the hive, eating honey during winter, but there are flowers to tended most days of the year!
No idea what was in your compost. If you're brave enough to find out, I'd be intruiged to hear about it - just don't go in there alone ....