The school you attend with the ED visa usually handles all the visa docs etc. If it's one of "those" ED visas, i would recommend an agent maybe, the one that organised it. Good luck for future!
THAT i can't say! Hopefully someone with knowledge of this new stamp being only valid via air (flights) or with land crossings as well can help! I THINK it should be same as before like the 30 day one? It's not factual though! Just a wild assumption GUESS! Someone knowledgeable should be along shortly to give the correct information! 😊