Ask them to explain what they can do for you when something goes wrong - because something always goes wrong on a business trip. You better get used to that fact now. Unless your company provides a company credit card, you may be expected to pay for all of your expenses up front, then file for reimbursement. Get this straight before you leave, or you may be very embarrassed taking your best client to dinner. Understand how to get cash advances and the documentation you will need to turn in when you get back.
Some companies are really picky about cash.
Don't get stuck. Introduce yourself to the people in accounting who will process your expense reports. They can be your best friends. Ask them what they need, how they like to receive information - then follow their advice. If you are spending thousands of dollars a year in travel expenses, you'll need a friend in accounting to get speedy reimbursement.