First of all, congratulations on being accepted! Maybe we'll see each other in a couple months, we've been considering applying in a future round. :)
I've talked with several people there about this and other topics. From what I hear, you should be taking around ~5K per person to support the first two months, while things get set up for the reimbursements. After that, it's just a matter of keeping receipts of everything and they'll reimburse in about 15 days time.
- when renting a place, you need to pay in advance so that's a huge bill right at the start which takes a while to be reimbursed
- plane tickets receipts should be in the name of the person traveling, NOT the company. They reimburse you personally.
- I think the topic above applies to all expenses. I'm not absolutely sure, so check the T&C and talk to the staff.
As for accepting, I think you definitely should. Every company I've seen going to Startup Chile has grown tremendously and really made a profit (both money & value) from going. Don't throw away the opportunity.
Hope that helps!