They would probably ask you questions with multiple visa exempt entries. I’m not sure if the answer “I work in Laos and have an apartment in Bangkok” assuming you would have the appropriate proof of work permit etc for Laos, would be enough to satisfy them, but it should be really.
A signature is a signature. They don’t really have ‘language’ as such. They are an individual mark that a person makes that is intended to be unique to that person.
The problem you may have with no visa is checking in for your flight if your return is more than 30 days away. Immigration would be ok with it and yes, you can extend for 30 days once here, and I understood perfectly what you meant by European citizen (EU passport).