Your friend is wrong about other visas. I my 10 year LTR visa is multiple entry. I don't need re-entry permits. You just have to know the parameters of your visa.
If you need to get a one year statement from your bank then find out how long it takes. Some provide it same day. Others may take up to a week. This will effect your timing to go to immigration.
I did the same with my OA visa for 6 years. I meet the income requirements for the LTR and already had the insurance even before it was a requirement for the OA. The LTR is 50,000 baht for 10 years. It is about the same as the 1,900 yearly fee depending on how you look at it. Surprisingly I really like not doing 90 day reports. I was very efficient about gathering the documents for yearly extensions but it is nice not doing that either. There are also no money in the bank requirements for the LTR.
I thought about in it 2022. It was a close call but I’m happy I got the LTR. The application was very easy as well.
When I made a claim on my Kasikorn accident insurance I just went into the bank and talked to a bank officer. I had hospital receipts. They paid into my bank account in 30 days.
Tax returns are one easy way to see all or some of your income. If you have other income then you need to talk to them about it. I’ve seen in LTR discussions that income other than straight work or government pensions can qualify. I believe they are looking at pre-tax income.