I think the most important thing is that you have to check the data once you upload your passport biodata page, you must ensure that the machine read data is entered correctly. upload the photo first and then manually go through each field and ensure it's entered correctly.
There is really no distinction on what you are doing once you get the visa. Whether remote work absent of Thai clients, or a cooking course, both activities are legal within the scope of the purpose of the visa.
if you extend the visa stay in Thailand you definitely will need to show the funds, if you leave and re-enter Thailand to get a new 180 day stamp there is a low possibility they might ask.