Do they expect debit cards?

Yes they do

Remember this is a flea market with 400 different vendors. Some will be set up for a debit card but most won't be. As with all flea markets, cash is accepted at every vendor.

Most do not have credit card ability.. There are arms there tho...99% don't take cards there

Yes

Yes they accept both debit and credit

Probably nothe but they do have an ATM in the building if you need cash.