Dear Khun Thanida,
Thank you for your clarifications. To arrive Thailand on 16 January 2016,
I will follow your instructions, which I understand as follows:
1. Standby to receive your documents by courier ETA NL : 28 or 29 December 2015.
2. Apply for the visa at Thai embassy on 4 January 2016 Monday.
3. Apply for Business Visa with Multiple re-entry and Duration of (each) stay 90 days.
4. After arriving Rayong, then apply work permit. (Must arrive Thailand within 30 days of date of visa issued.)
Please in your letter to Thai embassy NL, ask for such a visa to be valid for 1 year.
There is no mention of validity period in the application form. I suppose this is at their discretion