Do vendors except pre paid credit cards

If they accept major credit cards, and your card has a Visa or Mastercard logo, then yes. There is absolutely no difference on the payment end. I just went to see Slayer and I was warned that only a few vendors were even accepting cash. Ultimately, it deoends on the vendor. Your best bet (in every situation) is to have a little of both.

They deal with mostly cash now

Absolutley not