Looking at the game's damage the following would one shot me.

A chance from being Swallowed from Boko Baba (Varies between 1/2 to 6 Hearts damage)

Darknut's Jump Attack (4 Hearts)

Spin Attack from 1st Phantom Ganon (4 Hearts)

Fire Spit from Jalhalla (3 Hearts)

Being Swallowed or Hit by Molgera (4 Hearts)

Sword or Pink Orbs Attack from 2nd Phantom Ganon (4 Hearts)

I enjoy getting my money's worth out of games and therefore playing as many modes as I can (long run). With that logic in mind, playing the easiest to the most difficult is the most sensible instead of avoiding easy mode altogether.

Should be easy if you've played the game before. This is the easiest Zelda I've played.

Does that include the handheld Zeldas?  (Minish Cap, Spirit Tracks, Phantom Hourglass?)

Normal mode. The first playthrough for every Zelda is more of a relaxing one for me. Finding everything, enjoying the game at it's fullest. Then I play usually hero mode or 3 hearts-only.

I'll start in Hero mode but not a 3 hearts run. I'll leave the 3 heart run for later.

I said or because not every game in the series has a hero mode. TP, MM for instance.

O I thought you meant WW HD, not Zeldas in general.

no problem