Get used to your short hops and fast fall aerials. I played Smash 4 Ganondorf consistently for 4 years, and even after a month and a half since Ultimate released I still mess up tapping the jump button fast enough so I do short hops instead of full jumps, it's so sensitive now.
Another thing I find more difficult this time around is instant dash attacks, and Ganondorf's dash attack is one of his best tools. Dash into any grounded move is a blessing, but it made dash attacks a bit harder. I was used to flicking the analog stick + c-stick down for instant dash attack, but now you have to do c-stick left and right, and if you're timing is off you do a front tilt instead. The late, sourspot hit of dash attack is a good combo starter and finisher, and overall dash attack is just good damage and even KO move, as well as being useful dealing with projectile spammers who zone you out.
Get used to doing dash into front and down tilt. Dash into down tilt if they're grounded, and if they're approaching you from the air dash away from them and do a properly spaced front tilt.
These 2 videos show a lot of combos that are pretty straightforward but require some precise inputs.
https://www.youtube.com/watch?v=jLSp6umD3H4&
https://www.youtube.com/watch?v=1ddQrq1OE8w&
not that i would think, no! since shorthop > aerials are so easy now (hit the jump and a buttons simultaneously) you should be all set as long as you have a good gamesense!
I'd only recommend this if your opponent is in the air or they're open for a punish. Not every aerial is practical with the short hop aerial shortcut. Ganondorf's aerials will hit too high against most characters, he needs to fast fall with his aerials so he can reach low enough as well as for it to be safe on shield. It's a very useful tool for instant attacks and punishes but definitely don't rely only on this for your short hop aerials otherwise you will severely limit yourself.