You need to find a job first with a company that can help you apply for visa because they need to submit the paperwork. You can't get a visa and work permit, then only look for a job. It doesn't work like that.
The IO might speak to you in Thai and expect you to reply in Thai language. Maybe simple written test too if they suspect you're not actually learning. If they're not satisfied with your Thai language proficiency, they might deny you entry. Good luck.