Can GOTT's +1 target hexproof creatures?

No. Any ability or spell that requires the opponent to target is blanked by hexproof.

Does the +1 ability stick on a permanent that is flickered after the +1 ability resolved?

Thanks. I was wondering if it was like altered ego dodging hexproofing to copy a creature.

No it won't because the flickered permanent was exiled (left the game) and returned back

The only way to dodge hexproof is actually controlling the creature

And abilities that don't target, like Altered Ego.

Or have Bonds of Mortality on the field.

I think main strength now is in lords and swarm. Some peeps will still run and use graveyard more (all versions can do a bit of graveyard recursion with the Lilis they'll all be running, but not all versions will focus on that). Imho Innestrad versions of zombies weren't able to fill their yard fast/reliably enough to make their tribal payoffs (Diregraf, Elite) good enough. The more recent Grixis Reanimator or Grixis Slugs decks that run Amalgams and Haunted Dead but don't care about zombie tribal are miles better than the tribal zombie decks ever were.

I think new zombies will have options for more midrange that can swarm late with token spam, or aggressive tempo (lot of low cost options, zombies that tap creatures, menace, and In Oketra's Name). Suspect both of those will be stronger than graveyard focused zombies. The only real tool I can think of that those decks got is big Lili, but she fills the yard later game when I think they need more options that fill it early game so their 3 drops that care are big and bad on curve.

Yeah, I didn't really stop to think about what binding mummy can do, that card can lead to some disgusting things( makes me want to fit the 2/1 in the deck for instant speed tapping tho). It might solve the issues they seem to have with getting reach nicely.

Biggest gains for dimir graveyard zombies would probably the 2/1 that haunted dead can enable( good) compelling deterrence vs. embalming (meh) and the simmetrical discard mummy powering compelling deterrence( very meh).

I was about to write that.
Target is the key word that will inform you as to how hexproofy your hexproof card is.

Hexproofy has now been added to my vocabulary. Thank you for that.

Will Embalm work at instant speed? If so binding mummy will be pretty dope.

Embalm is only socery speed.

Aye. The best way to break Binding Mummy is to run a ton of cheap zombies to be able to trigger it at least 1 or more times a turn. Which also happens to work with most of the other stuff that zombies got. Wayward Servant wants lots of cheap zombies, so does Lord of the Accursed and In Oketra's Name, Graf Harvest doesn't mind having a lot of wank zombies around either. Plague Belcher even makes intentionally attacking/blocking unfavorably a viable source of reach.

Gideon of the Trials is to be banned in standard. How does this affect Magic Duels?

It won't, Standard rule changes do not effect Magic Duels.

Source?

Surely fake, they don't pre ban cards, lol.