What is the best strategy for applying for a retirement visa in Thailand as an Australian expat?

I'm an Aussie who plans to apply for retirement visa. Just got my 800 k Baht into local bank 2 weeks ago so I understand I cannot apply until 3 months has passed. My current tourist visa expires 25 January so must exit. Any suggestions on best strategy from here? I am renting condo in Bangkok and looking for easy border cross in any direction. And I suppose I would like to know if I can get back in with 2 month visa so will not have to exit again. I understand some visas can be extended from inside Thailand and am also curious about exit air tickets and if they are required in all circumstances. I very much appreciate your advice here.