What visa options are available for expats moving to Thailand, and what are the requirements for the OA and OX visas regarding bank account funds and dependents?

Hi, I am 51 and my wife is 38 and we will be moving to Thailand in January.

Trying to get my head around which visa to apply for.

My wife will be my dependent.

For the OA visa, do both my wife and I need to have 800k thb in a bank account or, as it is a joint application, is it sufficient to have just have 800k thb in 1 account. Also, does it have to be in Thai Baht, or can it be in a foregn currency but the equivalent to 800k thb?

Can the OA visa be extended every year for a year in Thailand? Or do I have to go back to my home country to procure the letter of no criminal record and medical certificate?

For the OX visa, is it for 5 years or 10 years? On the Thai embassy site it says 5 years each time, total 10 years. Does this mean that after 10 years I would have to switch to the OA visa?

I am eligible as a UK national. My wife is a Russian passport holder. Is she eligible as my dependent?

And again, for the 3 million thb in a bank account, can this be in a foreign currency or does it have to be in THB?

Thank you so much for answering these questions and I apologise if they have been asked before, but I couldn't find any link.