If you are over 50 you might find it easier to use a retirement visa which you can get before you travel to Thailand. No worries about return flights, much easier to open a bank account etc. Just requires a bit more in liquid finance
I don't give my passport to hotels. I use my driving licence. It has my passport number on it but not my nationality. Maybe that's where the mixup came from?
All applications for Thai visas are done online. Log into the evisa website and select your passport nation, your location and where you want to apply through. No need to travel unless you're currently in Thailand.