I think to avoid having to pay an extra fee to change the dog details with the KC, I would hold off changing her ownership until you've got her chipped. (As her microchip number will be printed on the owner registration certificate that the KC send you, so it'll avoid it having to be printed out again).
The 5 generation pedigree comes in 2 different sizes. The smaller one is green and is A4 size, the larger one is A3 sized and comes printed on beige card. (both sizes contain the same information). The five generation pedigree is useful to have if you're keen knowing the breeding behind your pup and want to research it, or if you intend to breed from your dog in the future (always contact your breeder to discuss this if it's something you're planning on doing as they will be the most informed about your pups suitability).
I personally like to have the 5 generation pedigree, although the A3 size isn't necessary in my opinion.
The breeds record supplement is only really of use if you want to see how many other litters have been bred/sired by different dogs in the UK for this year, and also which dogs have been tested under the KC health schemes, it includes their results.
Hope this helps

Mary xxx