sarah, I don't think little bits of fibrous root will regrow.
Never let it seed (I do )
It looks like feverfew, against is the 'not unpleasant fragrance' mentioned. I wouldn't want the taste/smell of feverfew in my food
It's not parsley or hemlock or any member of that family
that's not a clematis and I don't thinks it's a honeysuckle.
Possibly Jasminum beesianum
I'd put it somewhere shady outside.
I can't see the pic.
not Jack by the Hedge. I think it's one of the wild mustard/charlock type plants. Expect yellow flowers.
You could try replanting it but I'd give priority to forest flame if either set of roots have to be sacrificed.
It's not the best time for moving a deciduous tree but I think you should have it out of there.
a tree seedling of some sort, maybe a whitebeam or some other sorbus. You'll need to remove it, whatever it is it will be much bigger than the forest flame soon
it's been hedged pp, a shapeless blob. Thin some out and let others grow up. It will look more attractive
the pic hasn't loaded Dave
A very badly pruned hibiscus I think