All round fertiliser.

Yes, I generally only feed once per year, and that's in the spring. I completely empty the contents of my large composting bin and generously spread over the surface. The rain can wash the nutrients into the soil.

Next spring I'm going to do something slightly different, to add even more "nutrients" to the soil. As well as my well rotted down compost I'm going to mix in a fair bit of rotted down manure too from a local farm, and I might even add a bit of ash from my wood burning fire too.

It should all add to the richness of the soil and give the plants what they need for next summer's growth.

 

Yes - adding bulky organic material is the best food @Esoxlucius , as long as it isn't for plants that like poorer conditions! You can end up with lots of foliage and growth, and fewer flowers. It's great for shrubs/trees/hedges though. I've never used wood ash, but many people do. I've certainly used anything from my firepit [when I used it ] as I knew what the wood was, and where it came from.
Just be aware that farmyard manure is often full of 'stuff', because of the additives that many farm animals get in food etc. As long as it's well rotted down, it should be ok, and if you got it just now and kept it stored in a separate compost bin or area until spring, that should help.