I had to prove evidence of insurance prior to arriving to Thailand , as part of their approval requirements
I am not clear on your other question. Assuming you are meeting the income of 80 k USD during the past two years as required for the threshold for approval then not need to provide additional information. If lower amount but higher than 40usd then additional documentation is required
However you are best to contact BOI through their email for clarification
For me ,in addition to reportable income, I take funds on a monthly basis from non registered funds and provided bank statements to support the payments