Yes, you can come and go as many times as you please. You could technically enter the country 300 times in a year and it wouldn't be an issue (but your passport would be full of stamps 😅)
odd. They're the ones who issued the visa. I hope they let you in when you get here. If they ask, just explain what happened.
And for future reference, just write your name without a hyphen when dealing with Thai authorities. Keep it simple as they already complicate everything on their end.