The immigration only issue the visa up to the expiration date of your passport. If possible, get a new passport, and don't forget to move your old visa, to your new passport before doing the extension.

Your sim number is your permanent number, just fill 10 baht (minimum), it will add 30 days. Add 10baht * 12 times, you get one year. You can keep your number alive for max 12 months. You need to buy packages only when you arrive in Thailand (buy through app), no need to change number again.

If you’re a fresh graduate, it can be hard to get a job in a BOI company unless:

1. Your degree is highly specialized (e.g., AI, Data Science, some exceptions apply).

2. You're hired as an intern or trainee first, then converted after a period.

3. The company requests an exemption (can happen for rare skill sets or new industries).

The good news, very few companies under BOI, still confuse - use reliable agent, they will solve all the problems

1. Elite visa (expensive but worth)

2. Be a teacher (english or japanese)

3. DTV visa, need a company to hire you

4. Education Visa (for you and your child)

In the 2years times, start saving on your bank account. If you have enough funds, it's more easier to get visa. Good Luck.