Remember Jan 25th to Feb 2nd is Tet (New Year). The embassy will be closed for a week. Any applications submitted before the 25th won’t be finalized until after Feb 2nd
There are no more in person applicants. Last remaining embassies switched to 100% evisa on Jan 1st. However, you are correct. When there was an in person option, they would either check your documents or in a few locations approve you before payment. Unfortunately, no longer the case
Their website suggests that you should apply at least 30 days before your planned travel. Furthermore, there were 5 holidays during this time in which the embassy was closed. Don’t think it matters if you tell them your timeline.
As a reminder, Vietnam has a weeklong holiday the week after next. The embassy will be closed. So if you apply next week, you probably wont get it until early Feb.
If it is a country assigned to that embassy, it is fine if you are home in your country. I assume Tunisia would be assigned to another country. For example, Poland is responsible for Ukraine. You can state you are physically in Ukraine and still apply via the embassy in Warsaw Poland, as Ukraine is under their "jurisdiction"
Tunisia should be assigned to an embassy somewhere in the region. I am not sure though which one. For example, the Thai embassy in Nigeria is responsible for the following countries: Nationals from those countries would apply evisa from their country but select Nigeria. Not sure which one is assigned to Tunisa though, as many websites either dont work or are in French. Maybe the Thai embassy in Morocco or Egypt?
Almost everything is done online. You would receive your visa via email. There is a chance that the embassy would require an interview and that could be in person. There are a few embassies that still require you to pay in person as well. You should stay in the country you are applying via, throughout the processing time. So, if you are applying via the consulate in Tunisia, you should stay in Tunisia until you receive your electronic visa via email.