As you can tell, very personalized.

I NEVER trust any event totally (1/2 marathon distance or greater). I carry my own drink and fuel. Yes, I will re-fill w/ theirs if I need. I just want to eat/drink when I need/want to.

You SHOULD be hydrating and fueling at the distance you are now. Practice it. My coach recommended like 1/2 a gel instead of a full gel more frequently--it worked nicely. So whatever your fuel is.

As for walk breaks. Various reasons to have them...just keep short. Or try a real walk/run program. Then your run has to be a bit faster to make your overall time. Lots of folks to the "structured" walk break.

I agree with....hmmmmmm--michelem--you need to simulate a bit of your "race" in your training runs. Maybe not the whole run at race pace, but definitely the fueling and even how you attack the race (i.e. fast finish, etc).

Good luck.
I can only speak to many 1/2 marathons--I'll see how this experience plays out when I do my first full marathon (it's on the plan!)