Marriage to Thai is 400,000 baht for the visa/extension in Thailand. The exact amount you'll need for an embassy will be on the embassy's website, as it's not always the same.
Most browsers no longer show https in the browser bar. But Chrome says it's secure with SSL with a valid certificate.
Believe me, the browser is the least of your concerns when it comes to the security of your data. The Thai government has constant external data breaches and people inside selling data.