You said you wanted spoilers, so...
The town of Barovia is not deserted, people are just avoiding you. It contains at least one shop and dozens of occupants. However, prices at the shop are much higher than normal. Other towns also contain places to acquire goods and services, all with some amount of price inflation for at least some items.
For downtime training:
Training is a bit tricky. You'll doubtless be able to find someone willing to teach you, but you'll have a much harder time finding the time to learn. You're in the land of the devil. He won't wait 200 days.