Unfortunately I can't enlarge the picture so it's difficult to be 100% sure.
Tiny if it's an acid loving shrub you need ericaceous compost, otherwise a John Innes no.3 is the best. You may need to add grit depending on which shrub it is.
They're all the same it's a brand they all contain glyphosate.
If it only went on last summer you need to look for a framework this year Caroline. Pruning hard will give you strong new growth and you can choose the strongest stems to train to the framework you need.
Are you sure it's not the tap root Mr J? Seeds know which way is up or down, can't remember the reason. If you're having problems sow them vertically not flat.
Never grown them but as they are herbaceous perennials they should split on either spring or autumn.
I'd pinch them out a bit more nodlisab they'll throw put more side shoots.
First Swallow today in MidWales, lovely to see the first one. Plus big bonus a Brimstone butterfly feeding on primula vulgaris.
Ground elder John. If you don't mind using chemicals roundup is the thing you want. It is almost impossible to dig out, but some people prefer to try.
Gorgeous Dordogne, absolutely gorgeous.