1: Shape water. Either by you or a party member. If you rule this doesn't work, now we're getting into "this spell is limited by annoyance" and it's not a fun position to be in from a DM side.
4: I was talking about a wizard multi-classing over to grab 3 levels of sorcerer to grab meta-magic. I dismissed the idea as kind of a silly corner case.
On point 1 shape water is fine, but it won't stop snow from melting over 12 hours...
And on point 4, granted, but you need 7 levels of sorcerer to have enough sorcery points to affect a 7th level spell, which means a 13 wizard / 7 sorcerer could just barely pull off that stunt. And by level 20, well, considering they passed up 8th and 9th level spells to pull it off, I'd allow it.