The free trial gives you up to $200 or 30 days worth of activity, whichever comes first. If you remove the billing limit on the account before then, it will automatically roll over to a pay-as-you-go subscription if you hit one of those limits. So, no, you won't be charged for creating a VM, but the price you see will tell you how quickly your free credit will get used up.
Also, the price you see for the VM's is based on the machine running 24/7. If you shutdown your machines at the end of each session (through the Azure portal, not via remote desktop), you'll stop being charged for compute time. You'll still get charged for blob storage associated with those machines while they exist, but it's literally pennies. If you're working through the blue book, most of the time you'll only need one or two machines running at a time. So far, my invoices average about $30 per month, based on about 5-10 hours of play time per week, but obviously your mileage will vary depending on how efficiently you use your up-time.