Are you a billionaire? If not don't worry about it but to answer your questions I'll give it a shot.
Monitor accounts - well if they see deposits that don't match income they might inquire where it came from.
As for a tax on unrealized gains that's easy - many billionaires have lots of assets the bulk of which is stock that they have never sold. They want to tax it at a $.02 for every dollar over a certain amount (500 - 1 billion). So someone with 3 billion would pay $40 million w of their wealth which is Less than 1.4%.
If you owned stock then either the company that holds your stock sends them yearly what stocks you own, what you sold and bought, what gain or loss you sold it for.
Of curse it will pass the constitution what is your legal argument it won't as mine is that the government can make tax laws.