1. Libra and Globalcoin is just the different name for the same Facebook coin?
From what I understand, the project is called project Libra and the coin that they are about to create is Globalcoin which is made by Facebook. It's usual to say that it is facebook coin.
2. Now on 18th of June Facebook want to reveal the Libra (Globalcoin) project, but the coins will not be in sale? The lunch/sale is planned for the beginning of 2020?
3. Do you know how it will be possible to buy Facebook coins? Will this coin be listed on marketplaces like Bitstamp, Kraken ... or will it be
There's no exact date and announcement when they will launch or conduct the sale or if there will be.
4. Will the price be somehow regulated by Facebook or will it be fully open as other cryptocurrencies?
It is stable coin AFAIK so price won't fluctuate.