If an effect causes you to leave the battlefield, you resume being just a player. Your life total doesn't change. The Abian card that represented you moves to the appropriate zone.

If an effect adds or removes loyalty counters from Abian, you also gain or lose that much life. Similarly, if an effect causes you to gain or lose life, that many loyalty counters are put on or removed from Abian.

To activate your last ability, you can't pay more life than you have.

While Abian is on the battlefield, you're both a player and a permanent. You're a legendary planeswalker that's red and green.

If you control Abian but haven't become Abian, its loyalty abilities function as normal, drawing from its loyalty counters and not your life. Its last ability causes you, the player, to deal damage, although the source of the ability is Abian.