I did this once on a thai spouse visa, I paid a bill from the wrong account, but realised 20 minutes later and correct it, the immigration lady asked what happened I told her and she overlooked it, but I guess it will depend on the amount and if you corrected it quickly.
I've had several Fortuners and one Ford Ranger, both were super reliable, both will serve you well, The Ford parts are more expensive. Also take into consideration how far the service is.
The international driving permit is issued in your home country as a copy of your driving licence. On its own incant help you. You need to take your homecountry driving licence to a DLT office (department of land transport) and fill in a form and take a simple test.
Ministry of foreign affairs (MFA), in Bangkok, they have translation services in their building and can provide legalisation. If you get there early you might get it done the same day.