Remember that the "three certainties" aren't arbitrary requirements. Certainty of intention is just looking at whether a trust is what the settlor actually intended, or whether it is a gift or something out, with gifts you are still going through the same exercise - i.e. consider whether it is a gift that was ACTULLY intended, don't assume this - even if its not necessarily called certainty of intention.
You do need certainty of subject matter for anything that involves a transfer of property rights, including a gift. You can't transfer property rights if you can't identify with certainty what those rights are, he can't gift bottles of wine if you don't know what bottles of wine the dude was talking about, no court could possibly enforce that. Its a general principle of property law so the same set of cases apply
No certainty of objects for gifts.
RE: the last question, yes the problem is certainty of intention. Don't jump to conclusions, consider it both ways. You don't need to use the word "trust" necessarily, it is a question of what the settlor intended. Also you have a administrative unworkability problem