can I pay for my room using a purchase order from my place of employment?

Yes u can

Corporate accounts normally need a payment method/ credit card on file for bookings, you will need to follow the steps provided by your employer which usually means prepaying and turning in an expense report.

Probably not... They still function like a hotel even for corporate accounts. If the company has a credit card on file, you're probably good to go. Otherwise, you'll probably going to be expected to complete an expense report.