Is it required by law to appoint a lawyer to execute a valid will ?

My will leaves all my property and assets, a condo and bank account in Thailand to a friend. The will has been officially translated into Thai. I expect that he can obtain transfer of my a/c to his a/c (Both the same Thai banks) on presentation of the Death Certificate and Wiil to The Bank. I want to know if he can also transfer my condo in the same simple way. He is resident in Thailand, but US citiizen. Is it necessary by law to appoint a lawyer for this please ?

Selling my condo, how to calculate the transfer fees and taxes?

I had a look through some of the recently posted messages and replies but simply don't understand the personal income tax calculation.Is it calculated progressively? I have owned my condo for 8 years and am considering selling it for THB 6,5 mio. I understand the transfer fee of 2%, the stamp duty of 0,5%, no need for the specific business tax having owned my condo for 8 years - right - but am not sure about the personal income tax I will expect to pay. Appreciate any help you can extend and best regards, D