Simples,
If you really want the car:
Visit the name on the V5 to get clarity.
Check the V5 Vin with the car.
Phone the HP company to get clear title and then get it in writing.
Ermmm, no.
My dreams are usually nice dreams.
I would only begin to worry about it if you have the same dream on a regular basis, as those usually come true.
Best to check your insurance small print.
The dealer would have to pay a "surcharge" if you pay by card and this can vary from 2% to circa 4% depending on the card.
However Bank charges apply to cash transactions once/if lodged with the Bank.