Flying into bali shouldn't be an issue
It's usually recommended to take the batteries with you as carry-on (for safety reasons)
And take a reasonable amount (i would say less than 3) but you should be able to fly with more. You need to check your airline's regulation for this.
and if the custom's question you, make sure you explain you are a tourist (if they ask you to pay tax on it) and will not be leaving the phantom in Indonesia after your holidays.
As for what to see in Bali,
I just did a 2 days tour around Bali with the phantom 4 yesterday (not the best weather for video but the weather should clear by the time you are here)
Here is the video :