Can Twinned Spell target the same person twice?

With Polearm master feat and cover…

If a Death Tyrant reanimates a PC, do the PCs HPs regain to full?

Does the “Inured to Undead” feat for necromancy wizards stop the level 4 exhaustion?

Can you counterspell a counterspell?

Eldritch Knight/Arcane Trickster seems shouldn’t be terrible…