Is spell dmg worth at high levels?

[x3n0n]

As a matter of rules, when you've taken more damage than your HP, instead of vanilla "you can't take any more damage, just track death saves", instead you die when damage = 2 x HP. Each round until you're stable, you make a death save. On a success you stabilize. On a failure you take damage equal to 20% of your HP (rounded up).

Just to make sure I follow right:

Bob has 32 max HP.
Bob takes 37 damage (maxHP <= current damage < 2*maxHP), and is knocked out.
Bob succeeds at his first death save.

5E RAW: Bob is at 0 current HP with 1 success and 0 failures; not stable until he gets to 3 successes, or rolls a nat-20 death save and recovers to 1 HP.

MaxW rules: Bob is "at -5" (but really "at 5 damage above max HP"). As a result of "on a success you stabilize", he's stable. (Yes?) If so, taking any non-fatal damage just restarts the 6 HP (32/5, rounded down) "bleeding" per death save failure, until he succeeds a single death save?
Does a nat-20 death save do anything "special"?
If you're stable at damage >= maxHP for some amount of time (the same RAW 1d4 hours?), do you wake up with maxHP-1 damage?