Where you have your income ? I had my one year long term visa just showing my bank and pension statement in my country. Together those was enough. Maybe your situation is different.
It’s not easy I can say. Need so many documents so probably she need help from agency. Even every documents, bank account , invation letter, workplace testimony, support, personal application, interview in Bangkok and so on are clear and payments done, UK can deny visa ( mostly so).
Depends insurance company. Normally insurance accept local Thai driving license. Best option is your own country driving license and top of that international driving license. In your case it seems that you have to have Thai motorbike license for insurance. However, they have to confirm that it’s enough. My experience is that insurance companies try to find every holes to avoid paying.
-No license
-No Helmet
-Motorcycle not legal
-Driving under influence
Insurance companies have guys who only doing this job. Second step is GoFundMe app if something happens.
PS. 125 cc is enough everywhere if you don’t have a plan to have long trips in highways.