Yes. And prepare your backstory really good. Do not mention you're unemployed. Better to have a regular source of income. If you're an investor, you can start withdrawing X amount every month for next 3 months, and show that as your regular income from investment. Do not mention you're looking for new job or you are currently unemployed, instead say that you're taking a break from work and you have regular income from your investment to support your lifestyle. They may call you for an interview as well, so prepare accordingly and have proofs and documents ready. You can also say that your father is sponsoring you (prepare a sponsor letter, your father's bank statement and his employment details in that case).

Thai Consulates and Embassies in India are pretty strict. And since you mentioned unemployed in your application, your chances of rejection just skyrocketed. If your source of income is from investment, you should just have mentioned you're a stock trader and you get X amount of money every month from your investments as dividends to support your daily life. Never should you have mentioned "unemployed".

Secondly, you need to have 500K THB for at least 6 months. I was personally told this by Kolkata Consulate. I'm assuming it's true for all the consulates in India.

Thirdly, email the Embassy with your application number and ask for the reason for cancellation/rejection. Try to fix your mistake next time you apply.

Since you application has been recently rejected, apply after at least 2 months. And if possible apply from Thai Embassy in Laos, Jakarta, Cambodia or Vietnam. However I hear that a lot of DTV visa holders are being questioned by Immigration Officers at the airports if their DTV visa has been issued from Vietnam.

If you die first, all the martial properties and assets will go to your spouse, unless you had an will drafted that said otherwise. Also please note, a will cannot override the thai law, i.e, if you paid 100% for the house, you cannot claim 100% of the house after you die because that's against the Thai law. You'll only be able to claim 50% of the house.

Hence visit a lawyer and both you and your spouse should get a will drafted.

If you purchase the house on a loan or mortgage, be sure to get a life insurance with coverage equal to the price of the house. So that in case you die, your spouse won't be burdened with paying the mortgage, instead the life insurance will pay for it.

This is correct. You only need birth certificate. Birth certificate itself is the proof of who the legal father of the child is. What matters here is the "legal" father, not the "biological" father. Court document, DNA test, those are not required.

You can get a 90 days Non-O visa based on relative (i.e, your child) in your country. Visit Thailand on that visa, open a bank account, put 400K Baht in the account to season it. Then marry your girlfriend, and apply for 1 year extension based on marriage from within Thailand itself.

Don't expect them to fix it. They'll feign ignorance and say that it must have been you who entered the wrong details. They won't even go back and check in their system. They'll just tell you to reapply. But I wish you good luck. Let us know what happened.

Also you would only need to go through the hassle of reporting TM30 and 90 days if you plan on extending another 180 days in thailand. If you do not plan to extend, TM30 and 90 days reporting is not needed. You just leave the country before 180 days, nobody at airport immigration checks if you have filed TM30 and 90 days report or not during your departure from the country.

If landlord or hotel owner fails to file TM30 in time, it’s the tenant that gets fined when they visit immigration for extension/renewal. It’s so ridiculous. Why the average tourist and tenant have to pay the fine if it’s the landlord/owners responsibility to file the TM30? No action is ever taken against the owners, so why would they go out of their way to file TM30 for you? Hence you hear stories such as this all the time.

Most probably if overstay is only for couple days, you’ll only need to pay fine and they’ll put a overstay stamp in your passport and in their system. You’ll not get banned, but acquiring some future Thailand visas might become more difficult and they might ask you to come for an visa interview to explain your case before granting/denying you the visa you applied for.

Pay a bit more and reschedule your flight to a later date.