I despair.
You appear to be serious about comparing borrowing on a credit card with financing a £600 million to £1 billion development project.
Anyone who that thinks borrowing on a credit card to pay any bills that should have been provided for is a good way to run their finances needs lessons in domestic financial management. Interest rates when borrowing on a credit card are exorbitant; not as bad as from a pay-day loan shyster but nevertheless still to be kept as far away from as possible. A "good credit card rate" is currently 13-14%, and they often go higher than 30%.
You ask "The car comes back from its MOT with a list of repairs, it costs a bomb and you put that on the credit card - do those monthly repayments jump through the roof? " Of course they do. People who get into domestic financial trouble tend to start off borrowing on their credit card, default, become unable to get a credit card, and then resort to pay-day loan companies or worse. if your income is sufficient to allow you to cover for these unnecessary payments, then think how much better off you would be if you did some forward planning.
In the scenario you suggest the sensible thing to do would be to work out how long you will need to pay for the bill, then get a fixed-term loan from your bank, assuming you haven't been sensible enough to put funds by to cover from what really are likely to be inevitable future costs. Cars wear out. That shouldn't be a surprise.
The essential point on the financing of the stadium is the one I originally made. Finance facilities have to be serviced and repaid, and that will inevitably have an adverse effect on funds being available for other acquisitions until the loans are repaid or the extra income from the larger more flexible stadium more than counteract that.
I just thank providence that Daniel Levy and Matthew Collecott are responsible for the club's finances rather than you.