Don't worry, it's an annual so you just need to pull it out. It will be back next year, yank it out when you see the flowers so that it can't seed everywhere. No need for weedkiller.
Only if you eat them. Very young children must be supervised in the garden, older ones can be taught not to put things in their mouths unless they know it's edible.
Wild strawberries don't need any special nurturing, they often grow in thin poor soil in the wild. I suspect the dry conditions this year might affect the taste. However, all the ones I have popped into my mouth on country walks have been yummy!
Bolusanthus speciosus - it's beautiful. Usually used for bonsai, I'm not sure it's hardy outdoors in the UK.
I've found that Digitalis doesn't do at all well in pots, I'd put that one in the ground. As it's a biennial it will die next year anyway.
Cotoneasters are one of the largest groups and are difficult to ID to species, so good luck with identifying any further!
Which kind of Phlox? I don't bother with my creeping Phlox subulata.
Another vote for the hoe - I've got several different kinds and don't get on with any of them. My favourite tool is a hand fork.
Jingo, for future occasions just remember that you can wash off most "bugs" with a water spray, without doing harm to anything. Or if you know that they are damaging your plant, you can squash them. Free as well!
The leaves don't look right for C. vitalba but I agree, probably something derived from it.