2. Anyone spending unconfirmed transactions
This was never a good idea and has always been stated that 6 confirmations is the bare minimum and use zero at your own risk. It is an obvious area for improvement
Again, you are showing profound confusion. If you do not spend _your own_ unconfirmed coins you can be restricted to make only a _single_ transaction until you receive a confirmation... meaning you might easily be waiting an hour before you can make a second payment after making a first while waiting on a block.
Without the ability to spend unconfirmed transactions you cannot engage in many useful protocols like cross chain atomic swaps or coinswaps.
1. Wallet authors tracking spent bitcoins
According to GMaxwell no one cares, apparently.
A bit of a wrinkle there. Tracking if a payment has been made is what I was referring to above, but that text is referring to needing code to _unfuck_ a wallet after a chain of transactions has been disrupted with malleability. I'm not aware of any wallet that does this today, not even core. It too hard to do right, compared to just fixing the malleability. The distinction is that no amount of "modular" cosmetic ID can help that, because once the transaction chain is broken, it's broken. Previously I was responding above the kind of cosmetic issues you were discussing when you suggested that a non-normative ID could help.
but segwit just offloads the risk to a third party like any side-chain as was intended in the original design.
You are just spouting nonsense here. Who is the third party? What risk is offloaded? I think at this point you are literally just making things up and not even earnestly expressing your own confused views.
None of them are peculiar to SegWit but #3 requires it.
Lightning does not require segwit. Simply repeating it over and over again will not make it true.