Romania
Remember to take off your shoes when entering a house. Romanians are quite keen on keeping their carpets clean. Uhm, actually this is not exactly the reason. It's a sign of respect towards the host.
The Dracula Castle? Go without expectations. You’ll probably want to see something spectacular. Only your imagination after reading Stoker can create it.
This connects to the previous point: there are lots of beautiful castles around Transilvania. Go explore them. "Peleș" is just an example.
If you don't understand why Romanians eat pretzels all the time, be aware that this is one of the typical Romanian street food. It generally has different fillings, either savory or sweet.
Romanians are very welcoming. They're great hosts and will offer you a great deal of food and alcohol. Never say no. Also, don't forget that Romanians tend to insist when offering something and will expect you to do the same.
Palinca/Rachiu (and other local names) is supposed to stimulate your appetite, have it before your meal.
When introducing yourself to someone, shake their hands.
Remember to bring flowers or something to drink when invited to someone's house.