If i buy goods at Yiwu, better in cash or credit card ?

This will be my first trip to china.
I am planninh to visit many place inc yiwu market.

Some question i need to know...
1. Better i bring cash or credit card or what.,?
(For.. bus, shopping, taxi, hotel, etc)
2. Do every hotel in Yiwu have stuttle bus to Yiwu market ? Or its capable by walking?
3. Any regulation in China airport officer about the goods that i bring ?

Thanks.