There's no such thing as an LTV so it's not possible to accurately answer your question. If your father is getting a normal non-O visa with a 1 year retirement extension, the account will need to stay at 800,000 for the entire 90 day duration of the non-O visa, and then remain at 800,000 for 3 months after the extension date as well. After that it can never drop below 400,000 the rest of the year of the extension. Next year, instead of 800,000 in the bank, you can show the 12 monthly transfers of at least 65,000 baht to meet the extension requirements. Once that extension is issued, you won't even need the 400,000 anymore as long as you continue the monthly transfers.
If the visa is an LTR visa, none of the money in a Thai bank is relevant because that visa has nothing to do with funds in Thailand.
Where did you get your visa? If you got it at an embassy then no problem. Just make sure you have a TM30 filed for the address you're staying at and have a copy of the TM30 for your extension application.
If you got the non-O from an immigration office in Thailand then BIG problem. No other office will accept an application for an extension of a visa that was issued in a different immigration office.
Yes, you should apply for the 90 day non-O visa based on marriage to a Thai from the Thai embassy before you travel. This IS the marriage visa. You will not apply for another marriage visa in Thailand, you will simply apply for a 1-year extension (not a visa, not a non-O) based on marriage to a Thai.
You said you were married in Thailand, so if your marriage is already registered in Thailand then you'll be able to get the paperwork from any Amphur office. But if your marriage was not registered in Thailand, you will need to get all the paperwork made official while you're still in the US, including getting it stamped by the Thai embassy in the US.
It would be MUCH easier if your daughter gets her passport from the Thai embassy before she goes to Thailand. Otherwise she will be entering Thailand as a foreigner and will have to deal with some complications related to that, and won't be able to get rid of the requirements until she leaves Thailand by air and returns using her Thai passport. There's no reason to get her a non-O visa, let her enter visa exempt if you can't get the passport before you travel.
For shipping, you purchase space by the shipping container. I believe there are companies that will sell you a partial container shared with others. It's not something you can do by yourself at this level, and even if you tried you'd be raked over the coals with duty fees. So you need to find a shipping agent that works with shipping containers to Thailand.
that insurance will not meet the requirements for the visa then. You'll have to purchase one of the qualifying policies from the embassy approved list of Thai insurers. That's the catch of the OA visa.