If it is a land border, they usually will not stamp you in unless you make a fuss. In which case they will actually place a refusal stamp in your passport with a reason.
Airport bordet they will send you back on the same airline that you came from :(
In cases that you are detained and deported, you can be forced to buy a ticket elsewhere or your home country.
Pete Wright Any visa or visa exempt stamp can be extended 60 days if you are visiting immediate thai family (e.g. Thai spouse). Although i would always recommend at least a SE non-o which is fairly easy to obtain at an honorary consulate or neighbor consulate if you can prove marriage.
The 1 year extension requires a non-immigrant visa.
In theory, any consulate could do a notary service for any document they feel comfortable notorizing. In practice, I dont see how it would work (would their bosses allow it, international incident if you notorize fraudulent docs, etc).
normally you must go to the embassy/consulate that the passport was issued. E.g. If you are using a Spanish passport, you go to the Spanish embassy/consulate to get your income affidavit.