Planz in his 3 volume set of books on Gettysburg stated that the "Shoes Story" was fiction because at least 1 Brigade of Confederates had passed through Gettysburg on the 27th of June going to York, Pennsylvania. Had there in fact been shoes in Gettysburg at that time wouldn't they have been taken them then? However Heth would not have known about this since communication between the far flung elements of Lee's scattered army would have been minimal at best.
I will say that if this brigade did pass through Gettysburg on the 27th as Planz states they evidently left little impression for later historians to comment on. However this story does seem logical since Gettysburg was a hub of the roads network in that area of Pennsylvania. All Roads lead to Gettysburg so to speak.
So Stuart, or the lack of Stuarts cavalry, had nothing to do with Heth and the onset of the Battle itself. Stuart was doing his job in that he was distracting the Union Command with his manuvers close to Washington and dividing the attentions of the command structure in Washington and thereby causing Washington to interfer with Hooker and Meade's command decisions. It was only by a stroke of luck that Meade sent Hancock to Gettysburg to take command of the situation. It was Hancock's boldness in holding Cemetary Ridge that caused Meade to abandon the Pipe Creek plan and consentrate the Union Army there at Gettysburg rather than at Pipe Creek for the defence of Washington. Had it not been for Hancock, Meade would have probably withdrawn from Gettysburg, per previous plans, on the first night and regrouped at Pipes Creek. Gettysburg would have then been a Confederate Victory more that it was.