You need to ask the embassy you will be applying through, or check their website. They are the ones who will process the application and they decide what to accept and what not to accept.
If you are applying in Italy, they might accept documents in Italian, but they might require translations to English. The only way to know is to ask them.
neither. It's through the Thailand e-visa website, the only place you can apply for a visa through Thai embassies in Canada. The only place you could have applied for your visa originally