Where can I find FAQ of a specific service??

You can find FAQ in every service description, for example: https://www.vpsnet.lt/en/services/vps/faq

What are possible methods of payments?

You can pay by: bank wire transfer, international transfer in euro, VISA, MASTERCARD, MAESTRO and American Express credit cards, SMS, PayPal, WebMoney, Payza,  PaySera, SafetyPay, CashU, at MAXIMA shops etc.