How does Hagrid track Harry and the Dursleys when they try to escape the letter-sender and how does he travel during that period?

From this quote in Chapter Four-The Keeper of the Keys:

“Be grateful if yeh didn’t mention that ter anyone at Hogwarts,” he said. “I’m — er — not supposed ter do magic, strictly speakin’. I was allowed ter do a bit ter follow yeh an’ get yer letters to yeh an’ stuff — "

We see that Hagrid was using magic to follow the Dursleys as they drove around Britain trying to escape from the letter-sender, which also turns out to be Hagrid himself. I was wondering if anyone has a theory as to:

• How Hagrid tracks the Dursley’s movements.
• How Hagrid travels during this period (and how he got to the hut on the rock, which I am aware is a question that has been asked before but to which no conclusive answer has been given). Does he literally follow them, or does he track them remotely and turn up when they appear to have settled down for the night?

This quote in Chapter Five-Diagon Alley:

"How did you get here?" Harry asked, looking around for another boat.
"Flew," said Hagrid.
"Flew?"
"Yeah – but we’ll go back in this. Not s’pposed ter use magic now I’ve got yeh."

Shows that Hagrid was definitely using magic to travel. Harry also does not see the flying motorbike on the island so he couldn’t have been using that. In addition, Hagrid cannot ride brooms or thestrals (they cannot take his weight; there is a quote but I can’t find it), and he couldn’t have been using the Floo network as he arrived outside the hut and not in the fireplace.

In addition, Hagrid may or may not be able to apparate. If he could, it would certainly clear this up (saying to Harry that he "flew" would be a valid simplification for somebody who literally just learned that magic exists). Obviously, Hagrid did not learn to apparate at school as he was expelled in his third year (they teach apparation in sixth year). However, because Dumbledore knows he was innocent, has clearly helped him repair his broken wand and given him permission to use magic in emergencies (plus, Hagrid is a member of the Order) I think it is reasonably likely that Dumbledore has taught Hagrid how to apparate. Considering he feels so queasy on the Gringotts cart however, I am not convinced Hagrid would opt for apparation anyway.

I would love to hear some speculation.