I don't think metal would affect the water and it's less likely to crack if the whole thing freezes
Think nature, no nutcrackers out there. (Except the squirrels)
Cracked shell should be OK, removed shell, not OK, it will just rot
I'd plant the forsythia and buddleia in the ground unless it's frozen solid.. and the alliums.
Not the non hardy bulbs though, I assume the summer bulbs are the non hardy type, what are they?
Don't crack it open, just bury it. Pot or garden. It's how I grew my walnut trees, stuck them in a pot around now (leftovers from a Christmas party) they germinated when spring came, now producing their own nuts which the squirrels bury around the garden and they germinate to make more trees.
Paeonies aren't bulbs. Don't plant Sarah at bulb depth or you'll never see her again. Growing points just below the surface,
That bothers me less (probably because there are no pelagoniums in my life) than the use of one common name for all species in the genus. eg St John's Wort, Jerusalem Sage. A common name is something applied to one plant in the place where it comes from.
Twist the pipe end round or fit another one pointing to their garden
It takes many years to get a traditional flower-filled grass meadow Jim but you can get wild flowers this year and even more next year. Don't despair. The GQT team were probably just saying that all those old meadows are the result of hundreds of years grazing, hay cutting etc all done at the right time of year to allow seeding and reduce rampant grass/weed growth.
You can have wild flowers. I have them but I won't have a 'proper' meadow in my lifetime (same as yours )
I'd leave it alone. Let it see the light of day for a while and what it looks like next year. Daphne's have a reputation for not liking pruning. Might not be justified but they don't look like something that would prune well.
blanda are much more reliable, they self seed and multiply