yes very easy. If you arrive visa exempt they are currently stamping for 45 days, so after ASQ you have 29 days. Just visit your local immigration office and explain you want to convert to non O for retirement purposes. There is a very useful Facebook group call Thai Visa Advice. Join that and they will explain the process in great detail
Emirates for the airline, come on the visa exempt and convert to non O in country, you will have time to season your money during the under consideration period.. Depends how much you have to ship. Couriers are doing deals but sea freight would be cheaper.
When you upload from your pc you need to hit the upload button on tge Embassy site, just below your picture, you have to upload each one then after they are uploaded properly you can proceed
