I would have thought you'd need close to 150ml too kill everything
Sound like ants to me, same treatment as worm casts
Looks like you have a thick layer of thatch, I'd wait a month then heavily scarify, aerate and topdress with a sandy loam. you could then reseed any bare patches.
Birch will also regrow from coppicing, that will give you the multi stemmed effect without paying £200. Ginko I'm not sure about
Clematis armadii gets huge and doesn't particularly like pruning!!
I'm sure I've got these, don't mind scanning them and sending on
Leaves look like the same
Here's my paulownia starting it's climb into the skies
the way I see it is that most of the plants in our gardens are poisonous in some way or another, otherwise they would be classed as vegetables!
Hard prune each spring for ginormous foliage