every taxable person also has a 60.000 baht tax allowance per year. Married? If your spouse doesn't have income, you can use those 60K too. Kids? 30K per. Plus 2K per kid for education. Plus social security etc if that applies.. Your calculations are not correct. Even if just single, you don't pay one baht until you reach 210K/year.
Standard questions. Just answer and you should be fine. You have a proper visa for the duration and are not violating any terms of that visa by coming and going as much as you please for the validity of the visa. They are still allowed to ask though. And if for example they suspected that you are working while here on a tourist visa, they could refuse you entry. If you are a tourist, just answer the questions and go on.
a legal right to enter Thailand? 😂 Nope.. It's always up to the discretion of the immigration officer if they will let you in or not. A visa (or being eligible for a visa exempt stamp) is not a guarantee for entry. If they suspect you are violating the terms of whatever entry you are trying for, they absolutely can refuse you. You don't have any rights to enter Thailand if they refuse you. It's very rare though for a person with a proper visa to be refused. It is mostly because of excessive use of tourist visas or visa exempt entries.
I have a hard time thinking otherwise too. 1900 unless they change the cost of all extensions. At some point that might happen. But not from 1.900 to 10.000.
that is the price all news outlets wrote.. That doesn't mean it's true though. It would be very weird if this would be the only extension that cost more than the 1900 baht *all* other extensions cost.