I do not know if you plan on doing SR lines, but if that is the case, the ones that have a tendency to open and close, or be incredibly long are RRR and Gringotts. I wouldn't put Hagrid's into that category since it's so rare for it to have SR open. I'd say if you plan on getting on those rides do those early (although RRR is not accessible during EE).
Generally, the most popular rides are WWoHP ones, also I believe Kong still can have decent wait times, as well as Hulk since it's a thrill ride.
As for Hagrid's advice, all I can do is recommend keeping an eye on the main Hagrid Coaster post and keep track of what is happening until your trip and keep an eye on the wait times via Universal app. It's been reported a lot of times (but not all the time) that wait times are less than what is shown on the app and that wait times are dramatically increased in case there are delays.
Someone will have to confirm best transportation as I'm not an expert. I will say them not having transportation available for EE doesn't sound accurate, as that is one of the huge perks of staying on property. I know people at Cabana Bay like to walk to Sapphire Falls (which isn't a deluxe hotel, but only the deluxe hotels originally had boats) and take the boat just in general. However, since a lot of hotels do not have boats I would imagine a lot of guests take buses. Someone else will have to confirm when the buses start.