What should I know when traveling to apply for a NON-IMM F visa in KL, especially regarding re-entry permits and validation of my pre-authorization letter?

Hi Everyone. Advice. I'm travelling to KL to apply for a non-imm F visa. I'm travelling with my daughter. Both me and my daughter are currently on a an extension of stay based on non-imm o immigrant visa (dependent of a family member in Thailand – non-Thai). My daughter will not be applying for a visa but she will just travel with me to KL. We travel via Don Muang airport. Three questions:

1 – Is the Re-Entry Permit at Don Muang airport open 24/7? (Our flight is on Sunday at around 10am)

2 – Do you think I should also apply for a re-entry permit jut in

case the embassy for some reason does not issue me the visa? (I’m scared that I loose my current permit to stay which is until June if they don’t issue me the visa for some reason and I don’t have the entry permit. But I don’t know whether since I’m going out of the country to get a new visa then it is appropriate to get a re-entry permit or, if getting it, will just make the IO confused when I come back).

3 – I was issued the letter from my organisation which is addressed to the embassy in KL and which also certifies that my visa has been pre-authorized by the MFA on April 5. I have an appointment on April 6/7. Do you know if the letter is still valid? (I tried to contact the embassy of KL but so far to no answer, email the same). Please also note the visa I’m applying for is a NON-IMM F and not a non-Imm B.

Thanks for all the support!