July visit (Santiago de Chile)

Hello! I live in Bangkok but will be visiting Santiago in July. I've never been to South America and don't know anything about it. I'd appreciate if you could provide some local insight into getting around and places to go. Mainly I'd like to know:

1. The best way to get from airport to town, and within town. We have a group of 6 people. Do we need to book car with driver in advance?

2. Will I be able to use foreign credit cards easily? Or better to carry cash? In which currency?

3. Must go places?

Any advice is welcome! Thank you!!

Joey