@Nongnuch *******

You can indeed have both a work permit or another kind of visa and the Elite visa on your passport at the same time. Some Elite holders get a work permit or different visa while their Elite visa is still going on. If they're in Thailand, they visit an immigration office and get themselves stamped for their new visa. If they're outside of Thailand, when they enter Thailand, they tell immigration what visa they'd like to be stamped on.

You don't have to cancel your METV. When you enter Thailand and get the Elite visa affixed at the airport, you have the option to choose which visa you'd like to enter the country on. Let the immigration officer know your preference.

Even if you send the money, the visa officer will notice this unnatural transaction in her bank account. The transaction will look like someone has deposited the money in her account just so she can get the visa. This can be a potential reason for visa refusal.

Yes, Elite is a long term visa, so you can apply for visas for those countries in Thailand while being on an Elite visa. Those embassies might not take your application if you were on a short-term tourist visa, but since Elite is a long-term visa, they'll let you apply for visas from within Thailand.

Cash, maybe? (if the receiver doesn't have a bank account)

Those are Thailand Elite Visa Members Group and Thailand Elite Visa Q&A Group

A tourist visa applied in India will give your friend 60 days stay in Thailand. He can apply for another visa once the first one ends.

A better option would be to get a Multiple Entry Tourist visa, which is valid for 6 months. During this 6 months time, the person can stay 60 days per visit in Thailand.

Thai immigration may not ask for a return or onward ticket, but your airline may insist. I flew from the Philippines to Thailand without a return or onward ticket and I wasn't asked for anything. FYI, I'm a non-US passport holder.

I wouldn't suggest overstaying. If you must spend 20 days in Thailand, then when your 15 days VoA expires, visit a nearby country and return to Thailand and get a new VoA.

In their visa applications, most other countries ask if you've ever overstayed in any country, and you'll have to mention Thailand each time. You'll have to live with this overstay your entire life, so make a wise decision.

@Brandon ***********

I see the option to pay with a credit/debit card in my Bolt app.