Usual way is to take rooted pieces off.
They do sucker, if you are lucky.. Wish mine would.
Is it perhaps an Olearia macrodonta?
The biggest problem with beds in the glasshouse is removing and replacing the soil in them which you really need to do every few years or risk a build up of pathogens which reduce the cropping.
It certainly does look like Geum, probably urbanum, which is an terrible seed weed.
Not C, purpurescens either. Leaves are wrong. That is a fairly standard C. persicum. Kept in the right conditions it will flower for months. Not hardy though so once temps drop below 5c it is going to struggle.
Could be Lonicera maackii. In which case, no the berries are not eidble to humans.
Young one certainly could. they are also very good climbers. All you can really do is to protect the tree. Encircle it with wire netting or if your pocket runs to it try an electrified fence.
Does have the look of the native Privet which is deciduous rather than evergreen so the leaves are a lighter green than the normal hedging type.
Just have a look at what Woevales have done to Bridgemere. Used to be full of their own grown plants and now...............horrendous.