I’ve seen feedbacks of people allowed to convert to Thai licence only with a national driving licence from an English speaking country.
We could convert only our Norwegian licence previously if we got a confirmed translation of our licenses from our embassy in Bangkok. The embassy has stopped providing this service, so now it’s no way around a IDP to convert.
I’m sure practice regarding this varies between DLT, but it’s wort a try to check this up.
Tourist extensions are normally done within one or two days.
Some immigrations only let you apply within the last week, although most accept 30 day prior to due time.
I suggest you just go and get handed over their requirements. Normally you’ll need your passport with copy of ID-site and last stamps, one pass photo, receipt of your TM.30 address registration if they’ll ask for it and 1900 baht in cash. You apply on a TM.7 form at the immigration and can just ask your hotel or landlord of a receipt of your TM.30.
You don’t have a multiple entries visa, but you can buy a re-entry permit at the immigration or at the airport before you at 1000 baht for single and 3800 baht for multiple.
You only report after 90 days consecutive days in Thailand, so no notification is needed and the “90 days clock” restarts when you re-enter.
Varies between immigrations, some allows you to apply within the last 45 days, most within the last 30 days, but some only within the last week. The extension will always be added to your last day anyway. You can apply where you are at date and your latest TM.30 address registration is registered.
Check with the Thai embassy in Stockholm, but the only actual visa who will cover your whole stay is a one year Non O-A visa. The requirements are minimum 50 years old, income minimum 20,500 sek a month, an approved health insurance covering min 100K USD, health certificate and a police check up.