FWIW, my practice has been to refuel roughly an hour out of OSH. Last year I did it at LaCrosse, WI, and before it's been at Dubuque, IA. That gives me 3 1/2 hours of fuel after I arrive near RIPON. So far, I've only been held once, but that was for most of an hour, going round and round Green Lake. It was nice not to have any concerns at all about fuel.
On contacting ATC, they much prefer that you do rather than don't. I try to get flight following from my fuel stop until I can't any longer. Madison Approach is really pretty good about FF, but once they've concluded it just outside their area, Chicago Center can be iffy, although on more than one occasion, I've had Center FF almost to RIPON. On the way back out, I've been able to get Center FF as early as 20 miles west of OSH, which frankly surprised me--and it was really good, because I had to dodge some thunder-bumpers. I wasn't IFR current legally on that occasion, so I stayed VFR and got some terrific help from Center, all the way to just outside Dubuque. I suppose it depends a lot on the time of day and the traffic at that time.
As for contacting over-flown fields, that's only necessary for C & D towered airports, although calling fields on their CTAF is always wise, if you're actually within an area of potential conflict. With B airports, you must have a clearance to enter, and the magic words are, "xxxxx is cleared into the Class Bravo." If not cleared into it, the usual phrase is "do not enter Class Bravo", although sometimes it isn't said--you're just given a squawk and directions, so that the assumption must be that you're not cleared. With both C & D, as long as your call is returned with your tail number, you are in compliance.
Mostly, it's just a whole lot of fun!